Bio

Bio


Megan Hitchins is an Associate Professor of Medicine (Division of Oncology) and the Laboratory Head for the Hitchins' Translational Epigenetics Lab at Stanford University. Her research focus is the genetic and epigenetic mechanisms (and their interactions) underlying human disease, mainly as applied to cancer predisposition and outcomes. Her PhD training at University College London, UK was in Clinical Genetics. She undertook post-doctoral training at Imperial College London and University College London, before taking up a Faculty position at The University of New South Wales in Sydney, Australia. She has published ~60 peer-reviewed papers, reviews and book chapters. Her seminal work on the role of epimutations in human cancer predisposition and their variable patterns of inheritance in cancer-affected families have been published in first-author papers in leading journals, including the New England Journal of Medicine, Nature Genetics, Cancer Cell, and Gastroenterology, with Opinion Perspectives published in Nature Reviews Cancer. She received widespread media coverage for the discovery of non-Mendelian and Mendelian transmission patterns of constitutional MLH1 epimutations. From 2008 until her departure in 2013, 100% of her salary was covered through prestigious nationally competitive fellowships acquired from government organizations. Dr Hitchins' research in the genetic and epigenetic causes of cancer risk and outcomes continues, with clinical observational studies as well as molecular pathological epidemiology studies in cancer patients.

Academic Appointments


Honors & Awards


  • Career Development Level II Fellowship, Cancer Institute NSW, Australia (2011-2013)
  • Biomedical Level II Career Development Fellowship, National Health and Medical Research Council, Australia (2011-2013)
  • Career Development Fellowship, Cancer Institute NSW, Australia (2008-2010)
  • Post-doctoral Start-Up Award, Birth Defects Foundation, UK (1998)
  • PhD Scholarship, UK Medical Research Council (1995-1998)
  • Ron Nutkins Award for top grade at BS graduation, University of East London, UK (1994)

Professional Education


  • PhD, University College London, Clinical Genetics (1999)
  • Postdoctoral Fellow, Institute of Child Health, Molecular Embryology (2003)
  • Postdoctoral Fellow, Imperial College, Genomic Imprinting (2001)
  • BSc (Hons I), University of East London, Applied Biology (1994)

Teaching

Stanford Advisees


Publications

All Publications


  • Finding the needle in a haystack: identification of cases of Lynch syndrome with MLH1 epimutation Fam Cancer Hitchins, M. P. 2016
  • SNP rs16906252C>T is an expression and methylation quantitative trait locus associated with an increased risk of developing MGMT-methylated colorectal cancer (submitted; under review) Clin Cancer Res Kuroiwa-Trzmielina, J., Rapkins, R. W., Ward, R. L., Wang, F., Buchanan, D. D., Win, A. K., Clendenning, M., Rosty, C., Southey, M. C., Winship, I. M., Hopper, J. L., Jenkins, M. A., Olivier, J., Hawkins, N. J., Hitchins, M. P. 2016
  • The MGMT promoter SNP rs16906252 is a risk factor for MGMT methylation in glioblastoma and is predictive of response to temozolomide NEURO-ONCOLOGY Rapkins, R. W., Wang, F., Nguyen, H. N., Cloughesy, T. F., Lai, A., Ha, W., Nowak, A. K., Hitchins, M. P., McDonald, K. L. 2015; 17 (12): 1589-1598
  • Epigenetic Inactivation of BRCA1 Through Promoter Hypermethylation and Its Clinical Importance in Triple-Negative Breast Cancer CLINICAL BREAST CANCER Yamashita, N., Tokunaga, E., Kitao, H., Hitchins, M., Inoue, Y., Tanaka, K., Hisamatsu, Y., Taketani, K., Akiyoshi, S., Okada, S., Oda, Y., Saeki, H., Oki, E., Maehara, Y. 2015; 15 (6): 498-504
  • Constitutional epimutation as a mechanism for cancer causality and heritability? NATURE REVIEWS CANCER Hitchins, M. P. 2015; 15 (10)

    View details for DOI 10.1038/nrc4001

    View details for Web of Science ID 000361837900008

  • Milestones of Lynch syndrome: 1895-2015 NATURE REVIEWS CANCER Lynch, H. T., Snyder, C. L., Shaw, T. G., Heinen, C. D., Hitchins, M. P. 2015; 15 (3): 181-194

    Abstract

    Lynch syndrome, which is now recognized as the most common hereditary colorectal cancer condition, is characterized by the predisposition to a spectrum of cancers, primarily colorectal cancer and endometrial cancer. We chronicle over a century of discoveries that revolutionized the diagnosis and clinical management of Lynch syndrome, beginning in 1895 with Warthin's observations of familial cancer clusters, through the clinical era led by Lynch and the genetic era heralded by the discovery of causative mutations in mismatch repair (MMR) genes, to ongoing challenges.

    View details for DOI 10.1038/nrc3878

    View details for Web of Science ID 000350296100011

    View details for PubMedID 25673086

  • Allele Quantification Pyrosequencing® at Designated SNP Sites to Detect Allelic Expression Imbalance and Loss-of-Heterozygosity. Methods in molecular biology (Clifton, N.J.) Kwok, C., Hitchins, M. P. 2015; 1315: 153-171

    Abstract

    Pyrosequencing(®) is able to quantitate the level of a nucleotide at a designated germ-line or somatic variant, including single nucleotide polymorphisms (SNPs). SNPs within a gene of interest may be used to distinguish between the two genetic alleles and study their behavior in heterozygous individuals. With regard to cancer etiology and development, identification of alleles and the detection of allelic imbalances, such as transcriptional loss from one allele or loss-of-heterozygosity (due to deletion of one allele), within a tumor are particularly useful. Lynch syndrome, the most common form of hereditary bowel and uterine cancer, is caused by heterozygous germ-line mutations within the DNA mismatch repair genes and tumors develop following inactivation of the remaining functional allele within somatic tissues, usually by acquired loss-of-heterozygosity. MLH1 is the most frequently mutated gene in Lynch syndrome; however, some cases whose tumors display immunohistochemical loss of the MLH1 protein have no apparent mutation within the coding region of MLH1. Allelic loss of expression or reduced function of MLH1 can also result in the propensity to develop Lynch syndrome associated cancers. In this chapter we describe allele quantification Pyrosequencing assays designed at a common benign SNP within the MLH1 coding region for application to either DNA or mRNA (cDNA) templates, which enabled us to detect pathological allelic imbalances in such cases with suspected Lynch syndrome. Our allele quantification Pyrosequencing assays at the MLH1 c.655A > G (rs1799977) exonic SNP were applied to clinical specimens and detected both constitutional allelic expression loss and tumor loss-of-heterozygosity in some cases, facilitating the identification of the mechanistic cause underlying their cancer development. We provide detailed protocols for implementing these Pyrosequencing assays and illustrative examples of their application in patients.

    View details for DOI 10.1007/978-1-4939-2715-9_12

    View details for PubMedID 26103898

  • Chapter 12: Allele quantification pyrosequencing at designated SNP sites to detect allelic expression imbalance and loss-of-heterozygosity Pyrosequencing Kwok, C., Hitchins, M. P. edited by Lehmann, U., Tost, J. Springer Science+Business Media. 2015
  • Expression of GBGT1 is epigenetically regulated by DNA methylation in ovarian cancer cells BMC MOLECULAR BIOLOGY Jaco, F., Hitchins, M. P., Fedier, A., Brennan, K., Nixdorf, S., Hacker, N. F., Ward, R., Heinzelmann-Schwarz, V. A. 2014; 15
  • The MLH1 c.-27C > A and c.85G > T variants are linked to dominantly inherited MLH1 epimutation and are borne on a European ancestral haplotype EUROPEAN JOURNAL OF HUMAN GENETICS Kwok, C., Vogelaar, I. P., van Zelst-Stams, W. A., Mensenkamp, A. R., Ligtenberg, M. J., Rapkins, R. W., Ward, R. L., Chun, N., Ford, J. M., Ladabaum, U., McKinnon, W. C., Greenblatt, M. S., Hitchins, M. P. 2014; 22 (5): 617-624

    Abstract

    Germline mutations of the DNA mismatch repair genes MLH1, MSH2, MSH6 or PMS2, and deletions affecting the EPCAM gene adjacent to MSH2, underlie Lynch syndrome by predisposing to early-onset colorectal, endometrial and other cancers. An alternative but rare cause of Lynch syndrome is constitutional epimutation of MLH1, whereby promoter methylation and transcriptional silencing of one allele occurs throughout normal tissues. A dominantly transmitted constitutional MLH1 epimutation has been linked to an MLH1 haplotype bearing two single-nucleotide variants, NM_000249.2: c.-27C>A and c.85G>T, in a Caucasian family with Lynch syndrome from Western Australia. Subsequently, a second seemingly unrelated Caucasian Australian case with the same MLH1 haplotype and concomitant epimutation was reported. We now describe three additional, ostensibly unrelated, cancer-affected families of European heritage with this MLH1 haplotype in association with constitutional epimutation, bringing the number of index cases reported to five. Array-based genotyping in four of these families revealed shared haplotypes between individual families that extended across ≤2.6-≤6.4 megabase regions of chromosome 3p, indicating common ancestry. A minimal ≤2.6 megabase founder haplotype common to all four families was identified, which encompassed MLH1 and additional flanking genes and segregated with the MLH1 epimutation in each family. Our findings indicate that the MLH1 c.-27C>A and c.85G>T variants are borne on a European ancestral haplotype and provide conclusive evidence for its pathogenicity via a mechanism of epigenetic silencing of MLH1 within normal tissues. Additional descendants bearing this founder haplotype may exist who are also at high risk of developing Lynch syndrome-related cancers.

    View details for DOI 10.1038/ejhg.2013.200

    View details for Web of Science ID 000334600400010

    View details for PubMedID 24084575

  • Dawning of the epigenetic era in hereditary cancer. Clinical genetics Hitchins, M. P., Lynch, H. T. 2014; 85 (5): 413-416

    View details for DOI 10.1111/cge.12369

    View details for PubMedID 24588205

  • Application of a 5-tiered scheme for standardized classification of 2,360 unique mismatch repair gene variants in the InSiGHT locus-specific database NATURE GENETICS Thompson, B. A., Spurdle, A. B., Plazzer, J., Greenblatt, M. S., Akagi, K., Al-Mulla, F., Bapat, B., Bernstein, I., Capella, G., den Dunnen, J. T., Du Sart, D., Fabre, A., Farrell, M. P., Farrington, S. M., Frayling, I. M., Frebourg, T., Goldgar, D. E., Heinen, C. D., Holinski-Feder, E., Kohonen-Corish, M., Robinson, K. L., Leung, S. Y., Martins, A., Moller, P., Morak, M., Nystrom, M., Peltomaki, P., Pineda, M., Qi, M., Ramesar, R., Rasmussen, L. J., Royer-Pokora, B., Scott, R. J., Sijmons, R., Tavtigian, S. V., Tops, C. M., Weber, T., Wijnen, J., Woods, M. O., Macrae, F., Genuardi, M. 2014; 46 (2): 107-?

    Abstract

    The clinical classification of hereditary sequence variants identified in disease-related genes directly affects clinical management of patients and their relatives. The International Society for Gastrointestinal Hereditary Tumours (InSiGHT) undertook a collaborative effort to develop, test and apply a standardized classification scheme to constitutional variants in the Lynch syndrome-associated genes MLH1, MSH2, MSH6 and PMS2. Unpublished data submission was encouraged to assist in variant classification and was recognized through microattribution. The scheme was refined by multidisciplinary expert committee review of the clinical and functional data available for variants, applied to 2,360 sequence alterations, and disseminated online. Assessment using validated criteria altered classifications for 66% of 12,006 database entries. Clinical recommendations based on transparent evaluation are now possible for 1,370 variants that were not obviously protein truncating from nomenclature. This large-scale endeavor will facilitate the consistent management of families suspected to have Lynch syndrome and demonstrates the value of multidisciplinary collaboration in the curation and classification of variants in public locus-specific databases.

    View details for DOI 10.1038/ng.2854

    View details for Web of Science ID 000331208300006

    View details for PubMedID 24362816

  • Chapter 2: Prevention and Screening A multidisciplinary approach to diagnosis and management Hamilton, S. R., Sigurdson, E. R., Maresso, K. C., Patterson, S., Vilar, E., Hawk, E., Bishehsari, F., Jung, B. H., Lynch, H. T., Drescher, K., Sharma, P., Snyder, C., Lynch, J. F., Knezetic, J., Hitchins, M. H., Silberstein, P., Lanspa, S., Bownik, H., Chiorean, M. V., Yun, L. edited by Benson, A. B., Chakravarthy, A. B. 2014
  • Epigenetic changes associated with disease progression in a mouse model of childhood allergic asthma DISEASE MODELS & MECHANISMS Collison, A., Siegle, J. S., Hansbro, N. G., Kwok, C., Herbert, C., Mattes, J., Hitchins, M., Foster, P. S., Kumar, R. K. 2013; 6 (4): 993-1000

    Abstract

    Development of asthma in childhood is linked to viral infections of the lower respiratory tract in early life, with subsequent chronic exposure to allergens. Progression to persistent asthma is associated with a Th2-biased immunological response and structural remodelling of the airways. The underlying mechanisms are unclear, but could involve epigenetic changes. To investigate this, we employed a recently developed mouse model in which self-limited neonatal infection with a pneumovirus, followed by sensitisation to ovalbumin via the respiratory tract and low-level chronic challenge with aerosolised antigen, leads to development of an asthmatic phenotype. We assessed expression of microRNA by cells in the proximal airways, comparing changes over the period of disease progression, and used target prediction databases to identify genes likely to be up- or downregulated as a consequence of altered regulation of microRNA. In parallel, we assessed DNA methylation in pulmonary CD4(+) T cells. We found that a limited number of microRNAs exhibited marked up- or downregulation following early-life infection and sensitisation, for many of which the levels of expression were further changed following chronic challenge with the sensitizing antigen. Targets of these microRNAs included genes involved in immune or inflammatory responses (e.g. Gata3, Kitl) and in tissue remodelling (e.g. Igf1, Tgfbr1), as well as genes for various transcription factors and signalling proteins. In pulmonary CD4(+) T cells, there was significant demethylation at promoter sites for interleukin-4 and interferon-γ, the latter increasing following chronic challenge. We conclude that, in this model, progression to an asthmatic phenotype is linked to epigenetic regulation of genes associated with inflammation and structural remodelling, and with T-cell commitment to a Th2 immunological response. Epigenetic changes associated with this pattern of gene activation might play a role in the development of childhood asthma.

    View details for DOI 10.1242/dmm.011247

    View details for Web of Science ID 000322207900015

    View details for PubMedID 23611895

  • The role of epigenetics in Lynch syndrome FAMILIAL CANCER Hitchins, M. P. 2013; 12 (2): 189-205

    Abstract

    Recognition by Warthin of the familial clustering of colorectal and gynaecological cancers a century ago laid the foundation for the recognition of familial cancer. By tracking afflicted pedigrees, Lynch defined the clinical characteristics and argued for a heritable genetic component to this autosomal dominant cancer susceptibility condition, now termed Lynch syndrome. This was proven in the 1990s, with the discovery of deleterious germline mutations of the mismatch repair genes as its cause. Yet despite the genetic revolution at the turn of the twenty-first century, no pathogenic mutation was identifiable in approximately one-third of cases with suspected Lynch syndrome. In the past decade, the alternative mechanism of constitutional epimutation of the two major mismatch repair genes, MLH1 and MSH2, was identified in a proportion of these outstanding cases. This epigenetic defect, characterized by methylation and transcriptional inactivation of a single genetic allele within normal tissues, predisposes to the development of Lynch-type cancers. MSH2 and some MLH1 epimutations have been linked to genetic alterations within their vicinity and demonstrate dominant inheritance, whilst other MLH1 epimutations are reversible between generations and demonstrate non-Mendelian inheritance. This review charts the discovery of mismatch repair epimutations, their aetiological role in Lynch syndrome and the mechanistic basis for their variable inheritance patterns.

    View details for DOI 10.1007/s10689-013-9613-3

    View details for Web of Science ID 000322173700008

    View details for PubMedID 23462881

  • Identification of constitutional MLH1 epimutations and promoter variants in colorectal cancer patients from the Colon Cancer Family Registry GENETICS IN MEDICINE Ward, R. L., Dobbins, T., Lindor, N. M., Rapkins, R. W., Hitchins, M. P. 2013; 15 (1): 25-35

    Abstract

    Constitutional MLH1 epimutations manifest as promoter methylation and silencing of the affected allele in normal tissues, predisposing to Lynch syndrome-associated cancers. This study investigated their frequency and inheritance.A total of 416 individuals with a colorectal cancer showing loss of MLH1 expression and without deleterious germline mutations in MLH1 were ascertained from the Colon Cancer Family Registry (C-CFR). Constitutive DNA samples were screened for MLH1 methylation in all 416 subjects and for promoter sequence changes in 357 individuals.Constitutional MLH1 epimutations were identified in 16 subjects. Of these, seven (1.7%) had mono- or hemi-allelic methylation and eight had low-level methylation (2%). In one subject the epimutation was linked to the c.-27C>A promoter variant. Testing of 37 relatives from nine probands revealed paternal transmission of low-level methylation segregating with a c.+27G>A variant in one case. Five additional probands had a promoter variant without an MLH1 epimutation, with three showing diminished promoter activity in functional assays.Although rare, sequence changes in the regulatory region of MLH1 and aberrant methylation may alone or together predispose to the development of cancer. Screening for these changes is warranted in individuals who have a negative germline sequence screen of MLH1 and loss of MLH1 expression in their tumor.Genet Med 2013:15(1):25-35.

    View details for DOI 10.1038/gim.2012.91

    View details for Web of Science ID 000313460900003

    View details for PubMedID 22878509

  • The T genotype of the MGMT C > T (rs16906252) enhancer single-nucleotide polymorphism (SNP) is associated with promoter methylation and longer survival in glioblastoma patients EUROPEAN JOURNAL OF CANCER McDonald, K. L., Rapkins, R. W., Olivier, J., Zhao, L., Nozue, K., Lu, D., Tiwari, S., Kuroiwa-Trzmielina, J., Brewer, J., Wheeler, H. R., Hitchins, M. P. 2013; 49 (2): 360-368

    Abstract

    Clinical studies in patients with newly diagnosed glioblastoma treated with temozolomide have shown that the methylation status of the O(6)-methylguanine-DNA methyltransferase (MGMT) gene is both predictive and prognostic of outcome. Methylation of the promoter region of MGMT is the most clinically relevant measure of MGMT expression and its assessment has become integral in current and planned clinical trials in glioblastoma. Our study confirmed that MGMT methylation, assessed by pyrosequencing, is associated with a significant survival benefit in glioblastoma patients treated with temozolomide (either concurrently with radiotherapy or sequential treatment). More interestingly, our study demonstrated that a promoter variant, the c.-56C>T (rs16906252) single nucleotide polymorphism (SNP) located within a cis-acting enhancer element at the proximal end of MGMT, is associated with the presence of MGMT promoter methylation in de novo glioblastoma. Furthermore, we show that the overall survival of patients carrying both the SNP and MGMT methylation showed a strong survival benefit when compared to either molecular event on their own. Promoter reporter experiments in MGMT methylated glioblastoma cell lines showed the T allele conferred a ∼30% reduction in normalised MGMT promoter activity compared to the wild-type haplotype. This might account for the propensity of the T allele to undergo promoter methylation, and in turn, the improved survival observed in carriers of the T allele. An independent validation on larger cohorts is required to confirm the prognostic and predictive value of individuals carrying the T allele.

    View details for DOI 10.1016/j.ejca.2012.08.012

    View details for Web of Science ID 000313193000011

    View details for PubMedID 22975219

  • Epigenetic changes associated with disease progression in a model of childhood allergic asthma Dis Model Mech Collison , A., Siegle, J. S., Hansbro, N. G., Kwok, C., Herbert, C., Mattes, J., Hitchins, M. P., Foster, P. S., Kumar, R. K. 2013: 993-1000
  • Chapter 6: The role of epimutations of the mismatch repair genes in the development of Lynch syndrome related cancers DNA Alterations in Lynch Syndrome. Advances in molecular diagnosis and genetic counselling Hitchins, M. P. Springer. 2013: 101-134
  • THE T GENOTYPE OF THE MGMT C > T (RS16906252) ENHANCER SNP IS ASSOCIATED WITH PROMOTER METHYLATION AND LONGER SURVIVAL IN PATIENTS WITH GLIOBLASTOMA NEURO-ONCOLOGY McDonald, K. L., Rapkins, R., Zhau, L., Hitchins, M. 2012; 14: 8-8
  • Identification of new cases of early-onset colorectal cancer with an MLH1 epimutation in an ethnically diverse South African cohort CLINICAL GENETICS Hitchins, M. P., Owens, S. E., Kwok, C., Godsmark, G., Algar, U. F., Ramesar, R. S. 2011; 80 (5): 428-434

    Abstract

    Lynch syndrome, characterized by young-onset microsatellite unstable colorectal, endometrial and other cancers, is caused by germline mutations of the mismatch repair genes, most commonly MLH1, MSH2 and MSH6. Constitutional MLH1 epimutations, which manifest as soma-wide methylation and transcriptional silencing of a single allele, have been identified in a subset of patients with a Lynch syndrome phenotype in the absence of a mismatch repair mutation. This study aimed to determine if MLH1 epimutations predispose to the development of young-onset colorectal cancer in an ethnically diverse population of South African subjects. A total of 122 index cases with a diagnosis of colorectal cancer below 50 years of age, who had tested negative for a definitive pathogenic mutation of the key mismatch repair genes, were screened for constitutional MLH1 methylation in their leukocyte DNA. Monoallelic MLH1 epimutations were identified in two sporadic cases (1.6%): a male of black African descent and an Asian Indian female. Few alleles were affected by methylation in the female, indicating mosaicism. These cases provide further evidence of the aetiological role for MLH1 epimutations in cancer development and the requirement for sensitive molecular screening techniques to identify mosaic epimutations. Furthermore, while this mechanism is rare, it affects patients of multiple ethnic origins.

    View details for DOI 10.1111/j.1399-0004.2011.01660.x

    View details for Web of Science ID 000296022900006

    View details for PubMedID 21375527

  • Alu in Lynch Syndrome: A Danger SINE? CANCER PREVENTION RESEARCH Hitchins, M. P., Burn, J. 2011; 4 (10): 1527-1530

    Abstract

    Lynch syndrome is a hereditary cancer predisposition syndrome caused by germline loss of a DNA mismatch repair gene. In a significant proportion of cases, loss of function of the MSH2 mismatch repair gene is caused by large heterogeneous deletions involving MSH2 and/or the adjacent EPCAM gene. These deletions usually result from homologous malrecombination events between Alu elements, a family of short interspersed nuclear elements (SINE). Recent recognition that the extent of these deletions influences phenotypic outcome provided new impetus for fine-mapping the breakpoints. In doing so, Pérez-Cabornero and colleagues uncovered new evidence for Alu-mediated ancestral founder deletions within MSH2 in the Spanish Lynch syndrome population (as reported beginning on pages 1546 and 1556 in this issue of the journal). This is the first such finding to date and prompted a revisitation of the role of Alu elements in the causation of Lynch syndrome. Whether Alu density is a danger sign for genomic regions prone to rearrangement and what additional factors may be required to actuate these events remain to be discovered.

    View details for DOI 10.1158/1940-6207.CAPR-11-0417

    View details for Web of Science ID 000295620000002

    View details for PubMedID 21972078

  • Dominantly Inherited Constitutional Epigenetic Silencing of MLH1 in a Cancer-Affected Family Is Linked to a Single Nucleotide Variant within the 5 ' UTR CANCER CELL Hitchins, M. P., Rapkins, R. W., Kwok, C., Srivastava, S., Wong, J. J., Khachigian, L. M., Polly, P., Goldblatt, J., Ward, R. L. 2011; 20 (2): 200-213

    Abstract

    Constitutional epimutations of tumor suppressor genes manifest as promoter methylation and transcriptional silencing of a single allele in normal somatic tissues, thereby predisposing to cancer. Constitutional MLH1 epimutations occur in individuals with young-onset cancer and demonstrate non-Mendelian inheritance through their reversal in the germline. We report a cancer-affected family showing dominant transmission of soma-wide highly mosaic MLH1 methylation and transcriptional repression linked to a particular genetic haplotype. The epimutation was erased in spermatozoa but reinstated in the somatic cells of the next generation. The affected haplotype harbored two single nucleotide substitutions in tandem; c.-27C > A located near the transcription initiation site and c.85G > T. The c.-27C > A variant significantly reduced transcriptional activity in reporter assays and is the probable cause of this epimutation.

    View details for DOI 10.1016/j.ccr.2011.07.003

    View details for Web of Science ID 000294099700009

    View details for PubMedID 21840485

  • Methylation of the 3p22 region encompassing MLH1 is representative of the CpG island methylator phenotype in colorectal cancer MODERN PATHOLOGY Wong, J. J., Hawkins, N. J., Ward, R. L., Hitchins, M. P. 2011; 24 (3): 396-411

    Abstract

    Epigenetic silencing of cancer-related genes by promoter methylation is a frequent event in sporadic colorectal cancer. The CpG island methylator phenotype (CIMP+), in which discrete genes throughout the genome are simultaneously methylated, and long-range epigenetic silencing, whereby multiple genes within contiguous chromosomal regions are methylated, have been described in subsets of colorectal cancer. We previously reported the concurrent methylation of the mismatch repair gene MLH1 with a cluster of flanking genes in chromosome region 3p22 in sporadic colorectal carcinoma exhibiting microsatellite instability and the BRAF V600E mutation. Herein, we aimed to determine whether methylation of MLH1 and neighbouring 3p22 genes, singly or concomitantly, correlate with the germline c.-93G>A SNP within the MLH1 promoter, CIMP+ and other clinicopathological and molecular features of the tumours. By studying a cohort of 946 sporadic colorectal cancer cases, we show a strong association between concordant methylation of ≥ 3 of five 3p22 genes with CIMP+ and the BRAF V600E mutation (P<0.001). These associations were independent of microsatellite instability, as concomitant methylation of 3p22 genes other than MLH1 was found in microsatellite stable cancers. These findings show that long-range epigenetic silencing across 3p22 occurs in the context of CIMP+ and the BRAF V600E mutation, and only gives rise to microsatellite instability when this process encompasses MLH1. Furthermore, the strong relationship between long-range epigenetic silencing of 3p22 and CIMP+ provides further evidence that these two purportedly distinct epigenetic phenotypes represent a single entity with a common aetiology. Low-level methylation of MLH1 and flanking 3p22 genes, as well as the BRAF V600E mutation, were detected in the apparently normal colonic mucosa of a small number of cases whose tumours showed a similar molecular profile, suggesting that these concurring genetic and epigenetic events can occur as a field defect in neoplastic development.

    View details for DOI 10.1038/modpathol.2010.212

    View details for Web of Science ID 000287986600008

    View details for PubMedID 21102416

  • De novo constitutional MLH1 epimutations confer early-onset colorectal cancer in two new sporadic Lynch syndrome cases, with derivation of the epimutation on the paternal allele in one INTERNATIONAL JOURNAL OF CANCER Goel, A., Nguyen, T., Leung, H. E., Nagasaka, T., Rhees, J., Hotchkiss, E., Arnold, M., Banerji, P., Koi, M., Kwok, C., Packham, D., Lipton, L., Boland, C. R., Ward, R. L., Hitchins, M. P. 2011; 128 (4): 869-878

    Abstract

    Lynch syndrome is an autosomal dominant cancer predisposition syndrome classically caused by germline mutations of the mismatch repair genes, MLH1, MSH2, MSH6 and PMS2. Constitutional epimutations of the MLH1 gene, characterized by soma-wide methylation of a single allele of the promoter and allelic transcriptional silencing, have been identified in a subset of Lynch syndrome cases lacking a sequence mutation in MLH1. We report two individuals with no family history of colorectal cancer who developed that disease at age 18 and 20 years. In both cases, cancer had arisen because of the de novo occurrence of a constitutional MLH1 epimutation and somatic loss-of-heterozygosity of the functional allele in the tumors. We show for the first time that the epimutation in one case arose on the paternally inherited allele. Analysis of 13 tumors from seven individuals with constitutional MLH1 epimutations showed eight tumors had lost the second MLH1 allele, two tumors had a novel pathogenic missense mutation and three had retained heterozygosity. Only 1 of 12 tumors demonstrated the BRAF V600E mutation and 3 of 11 tumors harbored a mutation in KRAS. The finding that epimutations can originate on the paternal allele provides important new insights into the mechanism of origin of epimutations. It is clear that the second hit in MLH1 epimutation-associated tumors typically has a genetic not epigenetic basis. Individuals with mismatch repair-deficient cancers without the BRAF V600E mutation are candidates for germline screening for sequence or methylation changes in MLH1.

    View details for DOI 10.1002/ijc.25422

    View details for Web of Science ID 000286555700014

    View details for PubMedID 20473912

  • Detection of allelic imbalance in MLH1 expression by pyrosequencing serves as a tool for the identification of germline defects in Lynch syndrome FAMILIAL CANCER Kwok, C., Ward, R. L., Hawkins, N. J., Hitchins, M. P. 2010; 9 (3): 345-356

    Abstract

    Lynch syndrome is an autosomal dominant cancer susceptibility syndrome characterized by the early development of microsatellite unstable colorectal, endometrial and other cancers. Lynch syndrome is caused by germline heterozygous loss-of-function sequence mutations within the mismatch repair genes MLH1, MSH2, MSH6 or PMS2. Some individuals with Lynch syndrome have constitutional epimutations, characterized by promoter methylation and transcriptional inactivation of a single allele in normal somatic tissues, while others lack identifiable pathogenic changes in the germline. We hypothesized that analysis of the relative levels of allelic expression of MLH1 would assist in the identification of cryptic pathogenic defects of MLH1 in five presumed Lynch syndrome cases whose tumours demonstrated MLH1 loss, but whose causative mutation remained unidentified. We exploited the common benign c.655A>G SNP (rs1799977) within MLH1 exon 8 to distinguish between the two genetic alleles in heterozygous individuals and to study their transcriptional activity, using quantitative pyrosequencing assays. In one of the five patients we detected loss of expression of one allele and deletion of the other allele in the tumour, prompting renewed germline screening. A novel intronic splice mutation was subsequently identified, which resulted in loss of an entire exon from the transcript. This pyrosequencing assay also proved useful in demonstrating the gradual reversal of a constitutional MLH1 epimutation during lymphoblastoid cell culture, suggesting this defect may not be stably maintained in immortalized cells. Our findings illustrate that the study of allelic behaviour can complement conventional molecular analyses by providing new insight into the genetic or epigenetic mechanisms underlying disease.

    View details for DOI 10.1007/s10689-009-9314-0

    View details for Web of Science ID 000280922100014

    View details for PubMedID 20063070

  • Epimutations and cancer predisposition: importance and mechanisms CURRENT OPINION IN GENETICS & DEVELOPMENT Hesson, L. B., Hitchins, M. P., Ward, R. L. 2010; 20 (3): 290-298

    Abstract

    Germline sequence mutations in tumour suppressor genes can cause cancer predisposition syndromes. More recently, epimutations have also been proposed to cause at least one such syndrome, hereditary non-polyposis colorectal cancer (HNPCC). 'Epigenetic predisposition', is defined as an inherited propensity to an altered epigenetic state in normal tissues that confers a predisposition to disease. Genetic sequence variations acting in cis or trans may contribute to epigenetic variations. Understanding the origin of epimutations will inform cancer risk assessment and will also aid the design and application of new therapies that target the epigenome.

    View details for DOI 10.1016/j.gde.2010.02.005

    View details for Web of Science ID 000279446500015

    View details for PubMedID 20359882

  • Inheritance of Epigenetic Aberrations (Constitutional Epimutations) in Cancer Susceptibility Epigenetics and Cancer, pt A Hitchins, M. P. 2010: 201-243
  • Chapter 2: Historical Aspects of Lynch Syndrome In: Hereditary Colorectal Cancer Lynch, H. T., Hitchins, M. P., Shaw, T. G., Lynch, J. F., Roy, H. Springer Science+Business Media, LLC. 2010: 15-42
  • Inheritance of epigenetic aberrations (constitutional epimutations) in cancer susceptibility. Advances in genetics Hitchins, M. P. 2010; 70: 201-243

    Abstract

    The pathogenic role for heritable mutations in the DNA sequence of tumor suppressor and DNA repair genes has been well established in familial cancer syndromes. These germ line mutations confer a high risk of developing particular types of cancer, according to the gene affected, at a young age of onset when compared to sporadically arising cancers of a similar type. The widespread role for epigenetic dysregulation in the development and progression of sporadic cancers is also well recognized. However, it has only become apparent in recent years that epigenetic aberrations can also occur constitutionally to confer a similar cancer phenotype as a genetic mutation within the same gene. These epigenetic errors are termed "constitutional epimutations" and are characterized by promoter methylation and transcriptional silencing of a single allele of the gene in normal somatic tissues in the absence of a sequence mutation within the affected locus. This is best exemplified in Lynch syndrome, which is an autosomal dominant cancer susceptibility syndrome characterized by the early development of colorectal, uterine, and additional cancers exhibiting microsatellite instability due to impaired mismatch repair. Lynch syndrome is usually caused by heterozygous loss-of-function germ line mutations of the mismatch repair genes, namely MLH1, MSH2, MSH6, and PMS2. Tumors develop following an acquired somatic loss of the remaining functional allele. However, a subset of Lynch syndrome cases without genetic mutations instead has a constitutional epimutation of MLH1 or MSH2. These epimutations are associated with distinct patterns of inheritance depending on the nature of the mechanisms underlying them.

    View details for DOI 10.1016/B978-0-12-380866-0.60008-3

    View details for PubMedID 20920750

  • MGMT methylation is associated primarily with the germline C > T SNP (rs16906252) in colorectal cancer and normal colonic mucosa MODERN PATHOLOGY Hawkins, N. J., Lee, J. H., Wong, J. J., Kwok, C., Ward, R. L., Hitchins, M. P. 2009; 22 (12): 1588-1599

    Abstract

    O(6)-methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that restores mutagenic O(6)-methylguanine to guanine. MGMT methylation is frequently observed in sporadic colorectal cancer and was recently correlated with the C>T allele at SNP rs16906252, within the transcriptional enhancer element of the promoter. MGMT methylation has also been associated with KRAS mutations, particularly G>A transitions. We studied 1123 colorectal carcinoma to define the molecular and clinicopathological profiles associated with MGMT methylation. Furthermore, we assessed factors contributing to MGMT methylation in the development of colorectal cancer by studying the allelic pattern of MGMT methylation using SNP rs16906252, and the methylation status of neighbouring genes within 10q26 in selected tumours and matched normal colonic mucosa. MGMT methylation was detected by combined bisulphite restriction analysis in 28% of tumours and was associated with a number of characteristics, including CDKN2A methylation, absent lymphovascular space invasion and KRAS mutations (but not specifically with KRAS G>A transitions). In a multivariate analysis adjusted for age and sex, MGMT methylation was associated with the T allele of SNP rs16906252 (P<0.0001, OR 5.5, 95% CI 3.8-7.9). Low-level methylation was detected by quantitative methylation-specific PCR in the normal colonic mucosa of cases, particularly those with a correspondingly methylated tumour, as well as controls without neoplasia, and this was also associated with the C>T SNP. We show that the T allele at SNP rs16906252 is a key determinant in the onset of MGMT methylation in colorectal cancer, whereas the association of methylation at MGMT and CDKN2A suggests that these loci may be targets of a common mechanism of epigenetic dysregulation.

    View details for DOI 10.1038/modpathol.2009.130

    View details for Web of Science ID 000272207200009

    View details for PubMedID 19734844

  • Constitutional (germline) MLH1 epimutation as an aetiological mechanism for hereditary non-polyposis colorectal cancer JOURNAL OF MEDICAL GENETICS Hitchins, M. P., Ward, R. L. 2009; 46 (12): 793-802

    Abstract

    Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant syndrome characterised by a predisposition to early onset colorectal, endometrial and other cancers. The tumours typically exhibit microsatellite instability due to defective mismatch repair. HNPCC is classically caused by heterozygous loss-of-function mutations within the mismatch repair genes MLH1, MSH2, MSH6 and PMS2, but no pathogenic mutations are identified in a third of cases. In recent years, constitutional epimutations of the MLH1 gene, characterised by soma-wide allele specific promoter methylation and transcriptional silencing, have been identified in a handful of mutation negative HNPCC cases. In contrast to genetic mutations, MLH1 epimutations are reversible between generations and thus display non-Mendelian inheritance. This review focuses on the aetiological role of constitutional MLH1 epimutations in the development of HNPCC related cancers. The molecular characteristics, clinical ramifications and potential mechanism underlying this defect are discussed. Recommendations for the selection of cases warranting screening for MLH1 epimutations are proffered.

    View details for DOI 10.1136/jmg.2009.068122

    View details for Web of Science ID 000272288200001

    View details for PubMedID 19564652

  • Epigenetic changes in childhood asthma DISEASE MODELS & MECHANISMS Kumar, R. K., Hitchins, M. P., Foster, P. S. 2009; 2 (11-12): 549-553

    Abstract

    Childhood asthma is linked strongly to atopy and is characterised by a T helper 2 (Th2)-polarised immunological response. Epidemiological studies implicate severe lower respiratory tract viral infections, especially in early childhood, and repeated inhalational exposure to allergens as important synergistic factors in the development of asthma. The way in which these and other environmental factors induce stable alterations in phenotype is poorly understood, but may be explained on the basis of epigenetic changes, which are now recognised to underlie the establishment and maintenance of a Th2 response. Furthermore, ongoing asthmatic inflammation of the airways may be driven by alterations in the expression profile of regulatory microRNA genes, to which epigenetic mechanisms may also contribute. Thus, an understanding of epigenetic mechanisms in asthma has the potential to reveal new approaches for primary prevention or therapeutic intervention in childhood asthma.

    View details for DOI 10.1242/dmm.001719

    View details for Web of Science ID 000272832900007

    View details for PubMedID 19892885

  • Favoritism in DNA Methylation CANCER PREVENTION RESEARCH Hitchins, M. P., Ward, R. L. 2009; 2 (10): 847-849

    Abstract

    This perspective on Candiloro and Dobrovic (beginning on p. 862 in this issue of the journal) highlights the interplay between epigenetic aberrations and underlying DNA sequence changes and illustrates how these alterations may predispose individuals to cancer. Candiloro and Dobrovic clearly show that particular genotypes of the MGMT gene are associated with its methylation in healthy individuals. Aberrant MGMT methylation may identify individuals who could be targeted for cancer screening and chemoprevention strategies.

    View details for DOI 10.1158/1940-6207.CAPR-09-0178

    View details for Web of Science ID 000270819300002

    View details for PubMedID 19789293

  • Implementation of Novel Pyrosequencing Assays to Screen for Common Mutations of BRAF and KRAS in a Cohort of Sporadic Colorectal Cancers DIAGNOSTIC MOLECULAR PATHOLOGY Packham, D., Ward, R. L., Ap Lin, V., Hawkins, N. J., Hitchins, M. P. 2009; 18 (2): 62-71

    Abstract

    Activating mutations of the BRAF and KRAS genes cause constitutive stimulation of an important cell-signaling pathway promoting tumorigenesis, and are increasingly recognized as determinants of response to targeted cancer therapies. The V600E mutation accounts for most of the BRAF mutations in cancer, and KRAS mutations are predominantly encoded by nucleotide substitutions within codons 12 and 13. We designed novel pyrosequencing assays for the detection of the common "hotspot" mutations in these genes, which demonstrated analytical sensitivities of A transitions at position 2 of codons 12 and 13 being most prevalent. Both assays proved highly sensitive and specific when applied to clinical specimens, and were applicable to both fresh-frozen and formalin-fixed paraffin-embedded archival tissues. These assays would serve as a suitable platform for large-scale mutation detection in cancer specimens where the facility for pyrosequencing is available.

    View details for Web of Science ID 000266428500002

    View details for PubMedID 19430299

  • Favouritism in DNA methylation Cancer Prev Res Hitchins, M. P., Ward, R. L. 2009: 847-9
  • Differential expression of the embryo/cancer gene ECSA(DPPA2), the cancer/testis gene BORIS and the pluripotency structural gene OCT4, in human preimplantation development MOLECULAR HUMAN REPRODUCTION Monk, M., Hitchins, M., Hawes, S. 2008; 14 (6): 347-355

    Abstract

    In this paper, we examine the expression profiles of two new putative pluripotent stem cell genes, the embryo/cancer sequence A gene (ECSA) and the cancer/testis gene Brother Of the Regulator of Imprinted Sites (BORIS), in human oocytes, preimplantation embryos, primordial germ cells (PGCs) and embryo stem (ES) cells. Their expression profiles are compared with that of the well-known pluripotency gene, OCT4, using a primer design that avoids amplification of the multiple OCT4 pseudogenes. As expected, OCT4 is high in human oocytes, down-regulated in early cleavage stages and then expressed de novo in human blastocysts and PGCs. BORIS and ECSA show distinct profiles of expression in that BORIS is predominantly expressed in the early stages of preimplantation development, in oocytes and 4-cell embryos, whereas ECSA is predominantly expressed in the later stages, blastocysts and PGCs. BORIS is not detected in blastocysts, PGCs or other fetal and adult somatic tissue tested. Thus, BORIS and ECSA may be involved in two different aspects of reprogramming in development, viz., in late gametogenesis, and at the time of formation of the ES cells (inner cell mass (ICM) and PGC), respectively. However, in human ES cells, where a deprogrammed stem cell state is stably established in culture, an immunofluoresence study shows that all three genes are co-expressed at the protein level. Thus, following their derivation from ICM cells, ES cells may undergo further transformation in culture to express a number of embryo and germ line stem cell functions, which, in normal development, show different temporal and spatial specificity of expression.

    View details for DOI 10.1093/molehr/gan025

    View details for Web of Science ID 000257148900004

    View details for PubMedID 18467432

  • MLH1 germ-line epimutations: is there strong evidence of its inheritance? Gastroenterology Hitchins, M. P., Ward, R. L. 2008; 134 (1): 359-360

    View details for DOI 10.1053/j.gastro.2007.11.054

    View details for PubMedID 18166368

  • Erasure of MLH1 methylation in spermatozoa implications for epigenetic inheritance NATURE GENETICS Hitchins, M. P., Ward, R. L. 2007; 39 (11): 1289-1289

    View details for Web of Science ID 000250575900002

    View details for PubMedID 17968340

  • Epigenetic inactivation of a cluster of genes flanking MLH1 in microsatellite-unstable colorectal cancer CANCER RESEARCH Hitchins, M. P., Ap Lin, V., Buckle, A., Cheong, K., Halani, N., Ku, S., Kwok, C., Packham, D., Suter, C. M., Meagher, A., Stirzaker, C., Clark, S., Hawkins, N. J., Ward, R. L. 2007; 67 (19): 9107-9116

    Abstract

    Biallelic promoter methylation and transcriptional silencing of the MLH1 gene occurs in the majority of sporadic colorectal cancers exhibiting microsatellite instability due to defective DNA mismatch repair. Long-range epigenetic silencing of contiguous genes has been found on chromosome 2q14 in colorectal cancer. We hypothesized that epigenetic silencing of MLH1 could occur on a regional scale affecting additional genes within 3p22, rather than as a focal event. We studied the levels of CpG island methylation and expression of multiple contiguous genes across a 4 Mb segment of 3p22 including MLH1 in microsatellite-unstable and -stable cancers, and their paired normal colonic mucosa. We found concordant CpG island hypermethylation, H3-K9 dimethylation and transcriptional silencing of MLH1 and multiple flanking genes spanning up to 2.4 Mb in microsatellite-unstable colorectal cancers. This region was interspersed with unmethylated genes, which were also transcriptionally repressed. Expression of both methylated and unmethylated genes was reactivated by methyltransferase and histone deacetylase inhibitors in a microsatellite-unstable colorectal carcinoma cell line. Two genes at the telomeric end of the region were also hypermethylated in microsatellite-stable cancers, adenomas, and at low levels in normal colonic mucosa from older individuals. Thus, the cluster of genes flanking MLH1 that was specifically methylated in the microsatellite-unstable group of cancers extended across 1.1 Mb. Our results show that coordinate epigenetic silencing extends across a large chromosomal region encompassing MLH1 in microsatellite-unstable colorectal cancers. Simultaneous epigenetic silencing of this cluster of 3p22 genes may contribute to the development or progression of this type of cancer.

    View details for DOI 10.1158/0008-5472.CAN-07-0869

    View details for Web of Science ID 000249955500021

    View details for PubMedID 17909015

  • Brief report: Inheritance of a cancer-associated MLH1 germ-line epimutation NEW ENGLAND JOURNAL OF MEDICINE Hitchins, M. P., Wong, J. J., Suthers, G., Suter, C. M., Martin, D. I., Hawkins, N. J., Ward, R. L. 2007; 356 (7): 697-705

    Abstract

    Persons who have hypermethylation of one allele of MLH1 in somatic cells throughout the body (a germ-line epimutation) have a predisposition for the development of cancer in a pattern typical of hereditary nonpolyposis colorectal cancer. By studying the families of two such persons, we found evidence that the epimutation was transmitted from a mother to her son but was erased in his spermatozoa. The affected maternal allele was inherited by three other siblings from these two families, but in those offspring the allele had reverted to the normal active state. These findings demonstrate a novel pattern of inheritance of cancer susceptibility and are consistent with transgenerational epigenetic inheritance.

    View details for Web of Science ID 000244193300007

  • The role of MYH and microsatellite instability in the development of sporadic colorectal cancer BRITISH JOURNAL OF CANCER Colebatch, A., Hitchins, M., WILLIAMS, R., Meagher, A., Hawkins, N. J., Ward, R. L. 2006; 95 (9): 1239-1243

    Abstract

    Biallelic germline mutations in MYH are associated with colorectal neoplasms, which develop through a pathway involving somatic inactivation of APC. In this study, we investigated the incidence of the common MYH mutations in an Australian cohort of sporadic colorectal cancers, the clinicopathological features of MYH cancers, and determined whether inactivation of mismatch repair and base excision repair (BER) were mutually exclusive. The MYH gene was sequenced from lymphocyte DNA of 872 colorectal cancer patients and 478 controls. Two compound heterozygotes were identified in the cancer population and all three cancers from these individuals displayed a prominent infiltration of intraepithelial lymphocytes. In total, 11 heterozygotes were found in the cancer group and five in the control group. One tumour from an individual with biallelic germline mutation of MYH also demonstrated microsatellite instability (MSI) as a result of biallelic hypermethylation of the MLH1 promoter. Although MYH-associated cancers are rare in a sporadic colorectal population, this study shows that these tumours can develop through either a chromosomal or MSI pathway. Tumours arising in the setting of BER or mismatch repair deficiency may share a biological characteristic, which promotes lymphocytic infiltration.

    View details for DOI 10.1038/sj.bjc.6603421

    View details for Web of Science ID 000241751700018

    View details for PubMedID 17031395

  • Germline epimutations of APC are not associated with inherited colorectal polyposis GUT Hitchins, M., Suter, C., Wong, J., Cheong, K., Hawkins, N., Leggett, B., Scott, R., Spigelman, A., Tomlinson, I., Martin, D., Ward, R. 2006; 55 (4): 586-587

    View details for DOI 10.1136/gut.2005.087486

    View details for Web of Science ID 000236561900040

    View details for PubMedID 16531545

  • MLH1 germline epimutations as a factor in hereditary nonpolyposis colorectal cancer GASTROENTEROLOGY Hitchins, M., WILLIAMS, R., Cheong, K., Halani, N., Lin, V. A., Packham, D., Ku, S., Buckle, A., Hawkins, N., Burn, J., Gallinger, S., Goldblatt, J., Kirk, J., Tomlinson, I., Scott, R., Spigelman, A., Suter, C., Martin, D., Suthers, G., Ward, R. 2005; 129 (5): 1392-1399

    Abstract

    Hereditary nonpolyposis colorectal cancer (HNPCC) is caused by heterozygous germline sequence mutations of DNA mismatch repair genes, most frequently MLH1 or MSH2. A novel molecular mechanism for HNPCC has recently been suggested by the finding of individuals with soma-wide monoallelic hypermethylation of the MLH1 gene promoter. In this study, we determined the frequency and role of germline epimutations of MLH1 in HNPCC.A cohort of 160 probands from HNPCC families who did not harbor germline sequence mutations in the mismatch repair genes were screened for methylation of the MLH1 and EPM2AIP1 promoters by combined bisulfite and restriction analyses. Allelic expression and family transmission of MLH1 were determined using polymorphisms in intron 4 and the 3' untranslated region.One of 160 individuals had monoallelic MLH1 hypermethylation in peripheral blood, hair follicles, and buccal mucosa, indicative of a soma-wide alteration. Monoallelic transcription of the paternal MLH1 allele was shown using a heterozygous expressed polymorphism within the 3' untranslated region. The hypermethylated allele was maternally transmitted, however, the mother and siblings who inherited the same maternal homologue were unmethylated at MLH1, suggesting the epimutation arose as a de novo event.Germline MLH1 epimutations are functionally equivalent to an inactivating mutation and produce a clinical phenotype that resembles HNPCC. Inheritance of epimutations is weak, so family history is not a useful guide for screening. Germline epimutations should be suspected in younger individuals without a family history who present with a microsatellite unstable tumor showing loss of MLH1 expression.

    View details for DOI 10.1053/j.gastro.2005.09.003

    View details for Web of Science ID 000233296000008

    View details for PubMedID 16285940

  • MLH1 germ line epimutations as a factor in hereditary non-polyposis colorectal cancer Gastroenterology Hitchins, M. P., et al 2005: 1392-1399
  • Investigation of UBE3A and MECP2 in Angelman syndrome (AS) and patients with features of AS AMERICAN JOURNAL OF MEDICAL GENETICS PART A Hitchins, M. P., Rickard, S., Dhalla, F., de Vries, B. B., Winter, R., Pembrey, M. E., Malcolm, S. 2004; 125A (2): 167-172

    Abstract

    Angelman syndrome (AS) is an imprinted neurobehavioral disorder characterized by mental retardation, absent speech, excessive laughter, seizures, ataxia, and a characteristic EEG pattern. Classical lesions, including deletion, paternal disomy, or epigenetic mutation, are confirmatory of AS diagnoses in 80% of cases. Loss-of-function mutations of the UBE3A gene have been identified in approximately 8% of AS cases, failing to account for the remaining patient population, and there appears to be a higher prevalence of mutations in familial than sporadic cases. We screened UBE3A in 45 index cases of AS without obvious 15q11-13 abnormalities. Pathological mutations were identified in 3/6 (50%) familial and 4/39 (>10%) sporadic cases. By combining our data with those of the literature, we demonstrate statistically that the frequency of UBE3A mutations is significantly higher in the familial than sporadic subsets of AS. This indicates that an independent molecular mechanism or 'phenocopy' exists for the sporadic group. Rett syndrome (RS), caused by mutations of the MECP2 gene, and patients with deletions of 22q13.3 --> qter, have overlapping clinical features with AS. We screened 24 of the sporadic AS cases without detectable UBE3A mutations for mutations of MECP2, but found none. A separate cohort of 43 atypical patients with features common to AS and RS, in whom 15q11-13 lesions and 22q13.3 --> qter deletion had been ruled out, were also screened for MECP2 mutations. One male patient was mosaic for a frameshift mutation of this gene (previously reported). While MECP2 mutations can cause a phenotype reminiscent of AS in rare cases, they fail to account for the excess of sporadic patients with a definitive clinical diagnosis of AS.

    View details for DOI 10.1002/ajmg.a.20343

    View details for Web of Science ID 000220007800009

    View details for PubMedID 14981718

  • Conserved methylation imprints in the human and mouse GRB10 genes with divergent allelic expression suggests differential reading of the same mark HUMAN MOLECULAR GENETICS ARNAUD, P., Monk, D., Hitchins, M., Gordon, E., Dean, W., Beechey, C. V., Peters, J., Craigen, W., Preece, M., Stanier, P., Moore, G. E., Kelsey, G. 2003; 12 (9): 1005-1019

    Abstract

    Grb10/GRB10 encodes a cytoplasmic adapter protein which modulates coupling of a number of cell surface receptor tyrosine kinases with specific signalling pathways. Mouse Grb10 is an imprinted gene with maternal-specific expression. In contrast, human GRB10 is expressed biallelically in most tissues, except for maternal-specific expression of one isoform in muscle and paternal expression in fetal brain. Owing to its location in 7p11.2-p12, GRB10 has been considered a candidate gene for the imprinted growth disorder, the Silver-Russell syndrome (SRS), but its predominantly biallelic expression argues against involvement in the syndrome. To investigate the discrepant imprinting between mouse and human, we compared the sequence organization of their upstream regions, and examined their allelic methylation patterns and the splice variant organization of the mouse locus. Contrary to expectation, we detected both maternal and paternal expression of mouse Grb10. Expression of the paternal allele arises from a different promoter region than the maternal and, as in human, is restricted to the brain. The upstream regions are well conserved, especially the presence of two CpG islands. Surprisingly, both genes have a similar imprinted methylation pattern, the second CpG island is a differentially methylated region (DMR) with maternal methylation in both species. Analysis of 24 SRS patients did not reveal methylation anomalies in the DMR. In the mouse this DMR is a gametic methylation mark. Our results suggest that the difference in imprinted expression in mouse and human is not due to acquisition of an imprint mark but in differences in the reading of this mark.

    View details for DOI 10.1093/hmg/ddg110

    View details for Web of Science ID 000182660500006

    View details for PubMedID 12700169

  • Semi quantitative expression analysis of MDR3, FIC1, BSEP, OATP-A, OATP-C, OATP-D, OATP-E and NTCP gene transcripts in 1st and 3rd trimester human placenta PLACENTA Patel, P., Weerasekera, N., Hitchins, M., Boyd, C. A., Johnston, D. G., Williamson, C. 2003; 24 (1): 39-44

    Abstract

    Using real time RT-PCR, we have detected expression of seven genes that influence bile acid transport,MDR3, FIC1, BSEP, OATP-A, OATP-C, OATP-D and OATP-E, in normal human placenta. With the exception of OATP-C and OATP-E these genes were found to be differentially expressed in 1st trimester and 3rd trimester placentae. MDR3 gene expression was found to be up regulated four fold in 3rd trimester placentae compared to 1st trimester, OATP-A gene expression was down regulated eight fold, OATP-D was down regulated 17 fold, while FIC1 expression was reduced by 33 fold in the 3rd trimester. OATP-C and BSEP gene expression was not detected in the 3rd trimester placenta, while low levels of transcripts were detected in the 1st trimester placentae. Transcripts of the hepatic sinusoidal bile acid transporter, NTCP, were not detected in placenta.

    View details for DOI 10.1053/plac.2002.0879

    View details for Web of Science ID 000180467800007

    View details for PubMedID 12495658

  • DDC and COBL, flanking the imprinted GRB10 gene on 7p12, are biallelically expressed MAMMALIAN GENOME Hitchins, M. P., Bentley, L., Monk, D., Beechey, C., Peters, J., Kelsey, G., Ishino, F., Preece, M. A., Stanier, P., Moore, G. E. 2002; 13 (12): 686-691

    Abstract

    Maternal duplication of human 7p11.2-p13 has been associated with Silver-Russell syndrome (SRS) in two familial cases. GRB10 is the only imprinted gene identified within this region to date. GRB10 demonstrates an intricate tissue- and isoform-specific imprinting profile in humans, with paternal expression in fetal brain and maternal expression of one isoform in skeletal muscle. The mouse homolog is maternally transcribed. The GRB10 protein is a potent growth inhibitor and represents a candidate for SRS, which is characterized by pre- and postnatal growth retardation and a spectrum of additional dysmorphic features. Since imprinted genes tend to be grouped in clusters, we investigated the imprinting status of the dopa-decarboxylase gene (DDC) and the Cordon-bleu gene (COBL) which flank GRB10 within the 7p11.2-p13 SRS duplicated region. Although both genes were found to replicate asynchronously, suggestive of imprinting, SNP expression analyses showed that neither gene was imprinted in multiple human fetal tissues. The mouse homologues, Ddc and Cobl, which map to the homologous imprinted region on proximal Chr 11, were also biallelically expressed in mice with uniparental maternal or paternal inheritance of this region. With the intent of using mouse Grb10 as an imprinted control, biallelic expression was consistently observed in fetal, postnatal, and adult brain of these mice, in contrast to the maternal-specific transcription previously demonstrated in brain in inter-specific F1 progeny. This may be a further example of over-expression of maternally derived transcripts in inter-specific mouse crosses. GRB10 remains the only imprinted gene identified within 7p11.2-p13.

    View details for DOI 10.1007/s00335-002-3028-z

    View details for Web of Science ID 000180337900003

    View details for PubMedID 12514746

  • Chromosome 7p disruptions in Silver Russell syndrome: delineating an imprinted candidate gene region HUMAN GENETICS Monk, D., Bentley, L., Hitchens, M., Myler, R. A., Clayton-Smith, J., Ismail, S., Price, S. M., Preece, M. A., Stanier, P., Moore, G. E. 2002; 111 (4-5): 376-387

    Abstract

    Silver-Russell syndrome (SRS) is characterised by pre- and postnatal growth restriction (PNGR) and additional dysmorphic features including body asymmetry and fifth finger clinodactyly. The syndrome is genetically heterogeneous, with a number of chromosomes implicated. However, maternal uniparental disomy for chromosome 7 has been demonstrated in up to 10% of all cases. Three SRS probands have previously been described with a maternally inherited duplication of 7p11.2-p13, defining this as a candidate region. Over-expression of a maternally transcribed, imprinted gene with growth-suppressing activity located within the duplicated region, or breakpoint disruption of genes or regulatory sequences, may account for the phenotype in these cases. Here we describe two additional SRS patients and four probands with PNGR with a range of cytogenetic disruptions of 7p, including duplications, pericentric inversions and a translocation. An incomplete contig consisting of 80 PACs and BACs from the centromere to 7p14 was constructed. Individual clones from this contig were used as FISH probes to map the breakpoints in the six new cases and the three duplication probands previously described. Our data provide further evidence for a candidate SRS region at 7p11.1-p14. A common breakpoint region was identified within 7p11.2 in all nine cases, pinpointing this specific interval. The imprinting status of genes within the 7p11.1-p14 region flanked by the most extreme breakpoints have been analysed using both somatic cell hybrids containing a single full-length maternally or paternally derived chromosome 7 and expressed single nucleotide polymorphisms in paired fetal and maternal samples.

    View details for DOI 10.1007/s00439-002-0777-4

    View details for Web of Science ID 000179035300010

    View details for PubMedID 12384779

  • Characterisation of the growth regulating gene IMP3, a candidate for Silver-Russell syndrome JOURNAL OF MEDICAL GENETICS Monk, D., Bentley, L., Beechey, C., Hitchins, M., Peters, J., Preece, M. A., Stanier, P., Moore, G. E. 2002; 39 (8): 575-581

    View details for Web of Science ID 000177458700007

    View details for PubMedID 12161597

  • Identification and characterization of an imprinted antisense RNA (MESTIT1) in the human MEST locus on chromosome 7q32 HUMAN MOLECULAR GENETICS Nakabayashi, K., Bentley, L., Hitchins, M. P., Mitsuya, K., Meguro, M., Minagawa, S., Bamforth, J. S., Stanier, P., Preece, M., Weksberg, R., Oshimura, M., Moore, G. E., Scherer, S. W. 2002; 11 (15): 1743-1756

    Abstract

    Imprinted gene(s) on human chromosome 7 are thought to be involved in Russell-Silver syndrome (RSS), based on the fact that approximately 10% of patients have maternal uniparental disomy of chromosome 7. However, involvement of the known imprinted genes (GRB10 at 7p12, PEG10 at 7q21.3 and MEST at 7q32) in RSS has yet to be established. To screen for new imprinted genes, we are initially using somatic cell hybrids containing a paternal or maternal human chromosome 7. Transcripts located between D7S530 and D7S649 (a 1.5 Mb interval encompassing MEST ) were subjected to RT-PCR analysis using somatic cell hybrids. One transcript named MESTIT1 (for MEST intronic transcript 1) reproducibly showed paternal-specific expression. Upon further analysis, we found MESTIT1 to be (1) paternally (and not maternally) expressed in all fetal tissues and fibroblasts examined, (2) to be located in an intron of one of the two isoforms of MEST but transcribed in the opposite direction, (3) to be composed of at least two exons without any significant open reading frame, and (4) to exist as a 4.2 kb transcript in many fetal and adult tissues. We could also identify two isoforms of the mouse Mest gene as observed in humans, but it is still unknown if a murine ortholog of MESTIT1 exists. We also examined the imprinting status of MEST isoforms as a first step in assessing whether MESTIT1 might influence the allelic expression pattern of the sense transcript. MEST isoform 1 was determined to be exclusively expressed from the paternal allele in all fetal tissues and cell lines examined, whereas MEST isoform 2 was only preferentially expressed from the paternal allele in a tissue/cell-type-specific manner. Our results suggest that MESTIT1 is a paternally expressed non-coding RNA that may be involved in the regulation of MEST expression during development. MESTIT1 (also known as PEG1-AS) is now the third independent transcript (with MEST and COPG2IT1) identified at human chromosome 7q32 demonstrating paternal chromosome-specific expression.

    View details for Web of Science ID 000176969800006

    View details for PubMedID 12095916

  • Genomic imprinting in fetal growth and development. Expert reviews in molecular medicine Hitchins, M. P., Moore, G. E. 2002; 4 (11): 1-19

    Abstract

    Each somatic cell of the human body contains 46 chromosomes consisting of two sets of 23; one inherited from each parent. These chromosomes can be categorised as 22 pairs of autosomes and two sex chromosomes; females are XX and males are XY. Similarly, at the molecular level, two copies of each autosomal gene exist; one copy derived from each parent. Until the mid-1980s, it was assumed that each copy of an autosome or gene was functionally equivalent, irrespective of which parent it was derived from. However, it is now clear from classical experiments in mice and from examples of human genetic disease that this is not the case. The functional activity of some genes or chromosomal regions is unequal, and dependent on whether they have been inherited maternally or paternally. This phenomenon is termed 'genomic imprinting' and the activity or silence of an imprinted gene or chromosomal region is set during gametogenesis. Genomic imprinting involving the autosomes appears to be restricted to eutherian mammals, and has most likely evolved as a result of the conflicting concerns of the parental genomes in the growth and development of their offspring. When the normal pattern of imprinting is disrupted, the phenotypes observed in humans and mice are generally associated with abnormal fetal growth, development and behaviour, illustrating its importance for a normal intrauterine environment. The characteristics of imprinted genes, their regulation and the phenotypes associated with altered imprinting are discussed.

    View details for PubMedID 14987379

  • Investigation of the GRB2, GRB7, and CSH1 genes as candidates for the Silver-Russell syndrome (SRS) on chromosome 17q. Journal of medical genetics Hitchins, M. P., Abu-Amero, S., Apostolidou, S., Monk, D., Stanier, P., Preece, M. A., Moore, G. E. 2002; 39 (3): E13-?

    View details for PubMedID 11897833

  • Silver-Russell syndrome: a dissection of the genetic aetiology and candidate chromosomal regions JOURNAL OF MEDICAL GENETICS Hitchins, M. P., Stanier, P., Preece, M. A., Moore, G. E. 2001; 38 (12): 810-819

    Abstract

    The main features of Silver-Russell syndrome (SRS) are pre- and postnatal growth restriction and a characteristic small, triangular face. SRS is also accompanied by other dysmorphic features including fifth finger clinodactyly and skeletal asymmetry. The disorder is clinically and genetically heterogeneous, and various modes of inheritance and abnormalities involving chromosomes 7, 8, 15, 17, and 18 have been associated with SRS and SRS-like cases. However, only chromosomes 7 and 17 have been consistently implicated in patients with a strict clinical diagnosis of SRS. Two cases of balanced translocations with breakpoints in 17q23.3-q25 and two cases with a hemizygous deletion of the chorionic somatomammatropin gene (CSH1) on 17q24.1 have been associated with SRS, strongly implicating this region. Maternal uniparental disomy for chromosome 7 (mUPD(7)) occurs in up to 10% of SRS patients, with disruption of genomic imprinting underlying the disease status in these cases. Recently, two SRS patients with a maternal duplication of 7p11.2-p13, and a single proband with segmental mUPD for the region 7q31-qter, were described. These key patients define two separate candidate regions for SRS on both the p and q arms of chromosome 7. Both the 7p11.2-p13 and 7q31-qter regions are subject to genomic imprinting and the homologous regions in the mouse are associated with imprinted growth phenotypes. This review provides an overview of the genetics of SRS, and focuses on the newly defined candidate regions on chromosome 7. The analyses of imprinted candidate genes within 7p11.2-p13 and 7q31-qter, and gene candidates on distal 17q, are discussed.

    View details for Web of Science ID 000172718400002

    View details for PubMedID 11748303

  • Evolutionary conservation, developmental expression, and genomic mapping of mammalian Twisted gastrulation MAMMALIAN GENOME Graf, D., Timmons, P. M., Hitchins, M., Episkopou, V., Moore, G., Ito, T., Fujiyama, A., Fisher, A. G., Merkenschlager, M. 2001; 12 (7): 554-560

    Abstract

    The twisted gastrulation gene (tsg) encodes a secreted protein required for the correct specification of dorsal midline cell fate during gastrulation in Drosophila. We report that tsg homologs from human, mouse, zebrafish, and Xenopus share 72-98% identity at the amino acid level and retain all 24 cysteine residues from Drosophila. In contrast to Drosophila where tsg expression is limited to early embryos, expression is found throughout mouse and human development. In Drosophila, tsg acts in synergy with decapentaplegic (dpp), a member of the TGF-beta family of secreted proteins. The vertebrate orthologs of dpp, BMP-2 and -4, are crucial for gastrulation and neural induction, and aberrant signaling by BMPs and other TGF-beta family members results in developmental defects including holoprosencephaly (HPE). Interestingly, human TSG maps to the HPE4 locus on Chromosome 18p11.3, and our analysis places the gene within 5 Mbp of TG-interacting factor (TGIF).

    View details for Web of Science ID 000169627100011

    View details for PubMedID 11420619

  • No evidence for mosaicism in Silver-Russell syndrome. Journal of medical genetics Monk, D., Hitchins, M., Russo, S., Preece, M., Stanier, P., Moore, G. E. 2001; 38 (4): E11-?

    View details for PubMedID 11283207

  • Maternal repression of the human GRB10 gene in the developing central nervous system; evaluation of the role for GRB70 in Silver-Russell syndrome EUROPEAN JOURNAL OF HUMAN GENETICS Hitchins, M. P., Monk, D., Bell, G. M., Ali, Z., Preece, M. A., Stanier, P., Moore, G. E. 2001; 9 (2): 82-90

    Abstract

    The GRB10 gene encodes a growth suppressor and maps to human chromosome 7p11.2-p13. Maternal duplication (matdup) of this region has recently been associated with Silver-Russell syndrome (SRS), which is characterised by pre- and postnatal growth restriction, craniofacial dysmorphism and lateral asymmetry. Maternal uniparental disomy for chromosome 7 (mUPD7) occurs in approximately 7% of SRS patients. Exposure of a recessive allele due to isodisomy has been ruled out in five mUPD7 cases, suggesting genomic imprinting as the basis for disease. Assuming SRS patients with matdup of 7p11.2-p13 and mUPD7 share a common aetiology, this would implicate a maternally expressed gene from this interval, which is involved in growth inhibition. Murine Grb10 was identified as a maternally expressed gene by subtractive hybridisation using normal and androgenetic mouse embryos. Grb10 maps to the homologous region of proximal mouse chromosome 11, for which mUPD incurs reduced birthweight. A role for GRB10 in SRS was evaluated by determining its imprinting status in multiple human foetal tissues using expressed polymorphisms, and by screening the coding region for mutations in 18 classic non-mUPD7 SRS patients. Maternal repression of GRB10 was observed specifically in the developing central nervous system including brain and spinal cord, with biallelic expression in peripheral tissues. This is in contrast to mouse Grb10, and represents the first example of opposite imprinting in human and mouse homologues. While a role for GRB10 in mUPD7 SRS cases can not be ruled out on the basis of imprinting status, no mutations were identified in the patients screened.

    View details for Web of Science ID 000167133600002

    View details for PubMedID 11313740

  • Conflicting reports of imprinting status of human GRB10 in developing brain: How reliable are somatic cell hybrids for predicting allelic origin of expression? Reply AMERICAN JOURNAL OF HUMAN GENETICS Yoshihashi, H., Maeyama, K., Kosaki, R., OGATA, T., Tsukahara, M., Goto, Y. I., Hata, J., Matsuo, N., Smith, R. J., Kosaki, K. 2001; 68 (2): 544-545
  • Conflicting reports of imprinting status of human GRB10 in developing brain: How reliable are somatic cell hybrids for predicting allelic origin of expression? AMERICAN JOURNAL OF HUMAN GENETICS Mergenthaler, S., Hitchins, M. P., Blagitko-Dorfs, N., Monk, D., Wollmann, H. A., Ranke, M. B., Ropers, H. H., Apostolidou, S., Stanier, P., Preece, M. A., Eggermann, T., Kalscheuer, V. M., Moore, G. E. 2001; 68 (2): 543-544

    View details for Web of Science ID 000166524800028

    View details for PubMedID 11170901

  • Silver-Russell syndrome and ring chromosome 7 JOURNAL OF MEDICAL GENETICS Wakeling, E. L., Hitchins, M., Stanier, P., Monk, D., Moore, G. E., Preece, M. A. 2000; 37 (5): 380-380

    View details for Web of Science ID 000087136400011

    View details for PubMedID 10905891

  • Duplication of 7p11.2-p13, including GRB10, in Silver-Russell syndrome AMERICAN JOURNAL OF HUMAN GENETICS Monk, D., Wakeling, E. L., Proud, V., Hitchins, M., Abu-Amero, S. N., Stanier, P., Preece, M. A., Moore, G. E. 2000; 66 (1): 36-46

    Abstract

    Silver-Russell syndrome (SRS) is characterized by pre- and postnatal growth failure and other dysmorphic features. The syndrome is genetically heterogeneous, but maternal uniparental disomy of chromosome 7 has been demonstrated in approximately 7% of cases. This suggests that at least one gene on chromosome 7 is imprinted and involved in the pathogenesis of SRS. We have identified a de novo duplication of 7p11.2-p13 in a proband with features characteristic of SRS. FISH confirmed the presence of a tandem duplication encompassing the genes for growth factor receptor-binding protein 10 (GRB10) and insulin-like growth factor-binding proteins 1 and 3 (IGFBP1 and -3) but not that for epidermal growth factor-receptor (EGFR). Microsatellite markers showed that the duplication was of maternal origin. These findings provide the first evidence that SRS may result from overexpression of a maternally expressed imprinted gene, rather than from absent expression of a paternally expressed gene. GRB10 lies within the duplicated region and is a strong candidate, since it is a known growth suppressor. Furthermore, the mouse homologue (Grb10/Meg1) is reported to be maternally expressed and maps to the imprinted region of proximal mouse chromosome 11 that demonstrates prenatal growth failure when it is maternally disomic. We have demonstrated that the GRB10 genomic interval replicates asynchronously in human lymphocytes, suggestive of imprinting. An additional 36 SRS probands were investigated for duplication of GRB10, but none were found. However, it remains possible that GRB10 and/or other genes within 7p11.2-p13 are responsible for some cases of SRS.

    View details for Web of Science ID 000085033600006

    View details for PubMedID 10631135

  • Biallelic expression of IGFBP1 and IGFBP3, two candidate genes for the Silver-Russell syndrome JOURNAL OF MEDICAL GENETICS Wakeling, E. L., Hitchins, M. P., Abu-Amero, S. N., Stanier, P., Moore, G. E., Preece, M. A. 2000; 37 (1): 65-67

    View details for Web of Science ID 000084894400015

    View details for PubMedID 10691413

  • The search for the gene for Silver-Russell syndrome ACTA PAEDIATRICA Moore, G. E., Abu-Amero, S., Wakeling, E., Hitchins, M., Monk, D., Stanier, P., Preece, M. 1999; 88: 42-48

    Abstract

    Patients with Silver-Russell syndrome display intrauterine growth restriction and other dysmorphic features. No single genetic cause for this syndrome has been found, although there are a small number of familial cases and some patients with chromosomal rearrangements. Maternal uniparental disomy of chromosome 7 has been found in approximately 7% of patients with Silver-Russell syndrome. In five of these patients exhibiting maternal uniparental disomy, no common regions of isodisomy were found, thereby ruling out the expression of a recessive allele. It is most likely that one or more imprinted genes are responsible for the phenotype of Silver-Russell syndrome. Human chromosome 7 demonstrates homology with two imprinted regions on mouse chromosomes 6 and 11, which are equivalent to human chromosome regions 7q32 and 7p11-p13, respectively. We directly analysed the imprinting status of candidate genes from chromosome 7 that mapped to homologous imprinted regions in the mouse and also had a potential role in growth. The candidates were the genes that encode the epidermal growth factor receptor and the insulin-like growth factor binding proteins-1 and -3. All three of these candidate genes are localized to chromosome region 7p11-p13. Using intragenic polymorphisms as markers, we found that all three genes showed biallelic expression in different fetal tissues. Therefore, it is unlikely that these candidate genes are directly involved in producing the phenotype of Silver-Russell syndrome. Other candidates are under analysis, including two newly identified genes that are known to be imprinted.

    View details for Web of Science ID 000084472300009

    View details for PubMedID 10626544

  • Report of the fourth international workshop on human chromosome 15 mapping 1997. Cytogenetics and cell genetics Morton, C. C., Christian, S. L., Donlon, T. A., Driscoll, D. J., Fink, J. K., Gabriel, J. M., Gotway, G., Greally, J. M., Hitchins, M. P., Howard, H. C., Ji, Y., Leonard, S., Lerner, T., Magenis, E., Malcolm, S., Ohta, T., Rainier, S., Rees, M., Riley, B., Robinson, W. P., Saitoh, S., Schultz, R., Sell, S., Sharp, J. D., Nicholls, R. D. 1999; 84 (1-2): 12-21

    View details for PubMedID 10343092

  • GLUCOKINASE GENE POLYMORPHISMS - A GENETIC-MARKER FOR GLUCOSE-INTOLERANCE IN A COHORT OF ELDERLY FINNISH MEN DIABETIC MEDICINE McCarthy, M. I., Hitman, G. A., Hitchins, M., RIIKONEN, A., Stengard, J., Nissinen, A., TUOMILEHTOWOLF, E., Tuomilehto, J. 1994; 11 (2): 198-204

    Abstract

    Although mutations in the glucokinase gene are implicated in the pathogenesis of glucose intolerance in pedigrees with maturity-onset diabetes of the young, the role of such mutations in typical Type 2 diabetes is poorly characterized. We studied a cohort of elderly men born (between 1900 and 1919) in two Finnish communities and exhibiting a continuous spectrum of glucose tolerance at assessments made in 1984 and 1989. Individuals were typed at two polymorphic microsatellites straddling the glucokinase gene, GCK(3') (n = 169) and GCK(5') (n = 166): these two markers were in linkage equilibrium in this cohort. Significant associations between alleles at the GCK(3') marker and glucose tolerance were evident (p = 0.002), the frequency of the (z + 2) allele rising from zero in control subjects (n = 88 chromosomes) to 6.5% (n = 62) in subjects with impaired tolerance and 12.2% (n = 188) in subjects with diabetes. Mean 2-h glucose levels were 10.5 (9.6-11.4, 95% confidence interval) mmol l-1 in individuals with the (z + 2) allele and 8.1 (7.6-8.7) mmol l-1 in those without (p = 0.01, corrected for multiple comparisons). No association was evident between GCK(5') alleles and glucose tolerance. The GCK(3') microsatellite is a marker for abnormal glucose tolerance in this cohort of elderly Finnish men.

    View details for Web of Science ID A1994NB34500013

    View details for PubMedID 8200207

  • Positive association in the absence of linkage suggests a minor role for the glucokinase gene in the pathogenesis of Type 2 Diabetologia McCarthy , M. I., Hitchins, M. P., Hitman, G. A., Cassell, P., Hawrami, K., Morton, N., Mohan, V., Ramachandran, A., Snehalatha, C., Viswanathan, M. 1993: 633-641