One young sporadic CRC patient carried heterozygous mutations in both MLH1 and BRCA1. Three mutations (MLH1 p.Arg265Cys, MLH1 p.Tyr343Ter, and CHEK2 p.Ile158TyrfsTer10) were each found in two independent patients, and these were designated “founder” mutations. Here, CHEK2 is linked to colorectal carcinoma.