MRC1 and cancer: Germline pathogenic variants affecting any of the four MMR genes MLH1, MSH2, MSH6 or PMS2 underlie Lynch syndrome (LS), conferring a strong predisposition towards various cancers—predominantly colorectal and endometrial carcinoma, but also others including urothelial, ovarian, and upper gastrointestinal cancers, and sebaceous dermatological tumours [4].