title: Constitutive deficiency in DNA mismatch repair.
abstract: Mutations in the DNA mismatch repair (MMR) genes are associated with the inheritance of hereditary non-polyposis colorectal cancer, also known as Lynch syndrome, a cancer syndrome with an average age at onset of 44. Individuals presenting with colorectal cancer are diagnosed with Lynch I, whereas individuals who present with extra-colonic tumors (such as endometrial, stomach, etc.) are identified as patients with Lynch syndrome II. Recently, 30 families have been reported with inheritance of biallelic mutations in the MMR genes. Here we summarize the phenotype of individuals with inheritance of homozygous or compound heterozygous mutations in the MMR genes that result in a complete lack of protein or greatly compromised protein function. In contrast to individuals with Lynch syndrome I and II, individuals with no MMR function present with childhood onset of hematological and brain malignancies, whereas residual MMR function can also result in gastrointestinal cancers and an age of onset in the second to fourth decade. Individuals with biallelic MMR mutations often present with café-au-lait spots, regardless of the level of MMR function remaining. Thus, the inheritance of two MMR gene mutations is a separate entity from Lynch I or II or the subtypes Turcot and Muir-Torre.
authors.affiliation: Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: K E A
authors.initials: KE
authors.lastname: Felton
authors.forename: D M
authors.initials: DM
authors.lastname: Gilchrist
authors.forename: S E
authors.initials: SE
authors.lastname: Andrew
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000172:deficiency / Q000235:genetics; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000145:classification / Q000235:genetics* / Q000473:pathology; D053843:DNA Mismatch Repair; D045643:DNA Repair Enzymes / Q000172:deficiency / Q000235:genetics; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D006801:Humans; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000172:deficiency / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; C497172:MSH2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes