A multigene family that encodes proteins involved in mismatch repair. They are the human homologues of the MutS genes in S. cerevisiae, which are themselves homologues of the E. coli MutHLS mismatch repair system that involves the MutH, MutL, MutS, and MutU genes. The protein products of the human genes are MSH2, 3, 4, 5, and GTBP (MSH6). Defects in mismatch repair may arise by mutation in these genes or through imbalance in the expression of some relative to others. Mutations in the MSH2 gene result in hereditary nonpolyposis colorectal cancer-1 and an MSH3 frameshift mutation has been observed in an endometrial carcinoma. MSH4–MSH5 heterodimers bind uniquely to Holliday junctions. MLH1, PMS1 (MLH2), and PMS2 (MLH4) are homologues of the E. coliMutL gene and the yeast PMS (postmeiotic segregation increased-1 and -2) genes respectively.
Subjects: Medicine and Health.