Among these only a single variant was found in one of the four MMR genes that predispose to HNPCC.53,56 Neither did we identify pathogenic variants in the APC gene that predispose to FAP, nor did we observe homozygous or compound heterozygous germline variants in the recessive CRC predisposition genes MUTYH and NTHL1. This may be related to the fact that most Danish HNPCC and polyposis families are under surveillance by the national registry as Denmark has had a long tradition for registration and screening of HNPCC families. Here, MRC1 is linked to Familial adenomatous polyposis.