title: Functional analysis of human mismatch repair gene mutations identifies weak alleles and polymorphisms capable of polygenic interactions.
abstract: Many of the mutations reported as potentially causing Lynch syndrome are missense mutations in human mismatch repair (MMR) genes. Here, we used a Saccharomyces cerevisiae-based system to study polymorphisms and suspected missense mutations in human MMR genes by modeling them at the appropriate S. cerevisiae chromosomal locus and determining their effect on mutation rates. We identified a number of weak alleles of MMR genes and MMR gene polymorphisms that are capable of interacting with other weak alleles of MMR genes to produce strong polygenic MMR defects. We also identified a number of alleles of MSH2 that act as if they inactivate the Msh2-Msh3 mispair recognition complex thus causing weak MMR defects that interact with an msh6Delta mutation to result in complete MMR defects. These results indicate that weak MMR gene alleles capable of polygenic interactions with other MMR gene alleles may be relatively common.
authors.affiliation: Department of Medicine, Ludwig Institute for Cancer Research, UC San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Martinez
authors.forename: Richard D
authors.initials: RD
authors.lastname: Kolodner
mesh_terms: D000483:Alleles; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics; D053843:DNA Mismatch Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D005816:Genetic Complementation Test; D006801:Humans; D020412:Multifactorial Inheritance / Q000235:genetics*; D051718:MutS Homolog 2 Protein / Q000235:genetics; D000074081:MutS Homolog 3 Protein; D009154:Mutation / Q000235:genetics*; D011110:Polymorphism, Genetic; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C078444:MSH3 protein, human; D000074081:MutS Homolog 3 Protein; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein