The Finnish founder population and MLH1 mutations in hereditary colorectal cancer.

Identifying hereditary colorectal cancer genes is historically complicated by genetic heterogeneity. Founder populations simplify genetic architecture through reduced allelic diversity and extended linkage disequilibrium. This write-up explores how Finland's unique demographic history, driven by geographic isolation and severe population bottlenecks, established the distinct "Finnish disease heritage." In the 1990s, this regional homogeneity proved instrumental in successfully mapping recurrent germline MLH1 (MutL Homolog 1) founder mutations in Lynch syndrome.