ATM Polymorphism and hereditary nonpolyposis colorectal cancer (HNPCC) age of onset (United States)

Objective: We examined a G-to-A single nucleotide polymorphism of the ATM gene, to determine if it influences hereditary non-polyposis colorectal cancer (HNPCC) age of onset. HNPCC is caused by mutations in mismatch repair genes, especially hMLH1 and hMSH2. ATM germline mutations have been associated with breast and digestive cancers. In a smaller European study, the G-to-A polymorphism was associated with an increased risk of developing an HNPCC-related cancer within HNPCC families. Materials and methods: We genotyped 109 mismatch repair gene (MMR) mutation carriers from 53 HNPCC families for the ATM polymorphism using PCR and single strand conformational polymorphism (SSCP) analysis. We tested the association between the ATM genotypes and HNPCC age of onset by survival analysis. Results: The ATM polymorphism did not significantly modify HNPCC age of onset, nor overall risk, in our population. Conclusions: Although a modifier effect was not seen in our study, future studies that examine the polymorphism in combination with other genetic and environmental factors may elucidate an association. Revealing such associations in MMR mutation carriers may improve risk estimates and help to identify individuals who are genetically susceptible to developing HNPCC at an earlier age.