Lynch syndrome is an autosomal, dominantly inherited, multicancer syndrome caused by a germline pathogenic variant in one of the mismatch repair genes: MLH1, MSH2, MSH6, or PMS2. The population frequency of pathogenic variants in these genes is between one (0·36%) per 279 people and one (0·035%) per 2841 people.2 Here, MLH1 is linked to Lynch syndrome.