Disease expression differences between Finnish and non-Finnish path_MLH1 carriers could reflect population-specific environmental and behavioural factors or a lower penetrance of the Finnish founder path_MLH1 variants compared to other path_MLH1 variants but this study shows that these factors cannot have a major impact on the observed high cumulative risk of CRC in path_MLH1 carriers in the total PLSD cohort of path_MLH1 patients. This evidence concerns the gene MLH1 and colorectal carcinoma.