MRC1 and colorectal carcinoma: For example, Hampel et al. selected patients with pathogenic variants in at least one allele of an MMR gene in their tumour for germline MMR gene testing from 419 unselected CRC patients, identifying twelve (2.9%) LS gene carriers (2 MLH1, 5 MSH2, 1 MSH6, 4 PMS2).