Identification of constitutional MLH1 epimutations and promoter variants in colorectal cancer patients from the Colon Cancer Family Registry

Abstract

Purpose: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.Methods: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.Results: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.Conclusion: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

DOI: 10.1038/gim.2012.91

Extracted Key Phrases

0204020132014201520162017
Citations per Year

61 Citations

Semantic Scholar estimates that this publication has 61 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@inproceedings{Ward2013IdentificationOC, title={Identification of constitutional MLH1 epimutations and promoter variants in colorectal cancer patients from the Colon Cancer Family Registry}, author={Robyn Ward and Timothy A. Dobbins and Noralane M. Lindor and Robert W. Rapkins and Megan P . Hitchins}, booktitle={Genetics in Medicine}, year={2013} }