In February 2017 NICE recommended pre-screening all colorectal cancers with either MSI or IHC with additional testing for MLH1 methylation and BRAF V600E to rule out somatic involvement of MLH1.[15] This was extended to all endometrial cancers following identification of a similar 3% germline mutation rate for MMR genes in the UK to colorectal cancer [16, 17]. This evidence concerns the gene MRC1 and colorectal cancer.