N-acetyltransferase 2 influences cancer prevalence in hMLH1/hMSH2 mutation carriers.

Hereditary nonpolyposis colorectal cancer (HNPCC), an inherited cancer predisposition syndrome, has been associated with germline mutations in DNA mismatch repair (MMR) genes. Because a deficiency in MMR does not predict a specific cancer phenotype, modifying genes may account in part for the variation in disease expression. We determined the N-acetyltransferase 2 (NAT2) genotype in 26 unaffected and 52 cancer-affected hMLH1/hMSH2 mutation carriers coming from 21 Swiss HNPCC families. Slow acetylators were found to be significantly (P < 0.03) more prevalent in the group of affected mutation carriers. Our results suggest a protective effect of the NAT2 rapid acetylator phenotype, an observation that could have implications for genetic counseling and management of MMR gene mutation carriers.