title: Functional analysis of MSH2 unclassified variants found in suspected Lynch syndrome patients reveals pathogenicity due to attenuated mismatch repair.
abstract: BACKGROUND
  Lynch syndrome, an autosomal-dominant disorder characterised by high colorectal and endometrial cancer risks, is caused by inherited mutations in DNA mismatch repair (MMR) genes. Mutations fully abrogating gene function are unambiguously disease causing. However, missense mutations often have unknown functional implications, hampering genetic counselling. We have applied a novel approach to study three MSH2 unclassified variants (UVs) found in Dutch families with suspected Lynch syndrome.
  
  
  METHODS
  The three mutations were recreated in the endogenous Msh2 gene in mouse embryonic stem cells by oligonucleotide-directed gene modification. The effect of the UVs on MMR activity was then tested using a set of functional assays interrogating the main MMR functions.
  
  
  RESULTS
  We recreated and functionally tested three MSH2 UVs: MSH2-Y165D (c.493T>G), MSH2-Q690E (c.2068C>G) and MSH2-M813V (c.2437A>G). We observed reduced levels of MSH2-Y165D and MSH2-Q690E but not MSH2-M813V proteins. MSH2-M813V was able to support all MMR functions similar to wild-type MSH2, whereas MSH2-Y165D and MSH2-Q690E showed partial defects.
  
  
  CONCLUSIONS
  Based on the results from our functional assays, we conclude that the MSH2-M813V variant is not disease causing. The MSH2-Y165D and MSH2-Q690E variants affect MMR function and are therefore likely the underlying cause of familial cancer predisposition. Since the MMR defect is partial, these variants may represent low penetrance alleles.
authors: Division of Biological Stress Response, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Eva A L
authors: EA
authors: Wielders
authors: Jan
authors: J
authors: Hettinger
authors: Rob
authors: R
authors: Dekker
authors: C Marleen
authors: CM
authors: Kets
authors: Marjolijn J
authors: MJ
authors: Ligtenberg
authors: Arjen R
authors: AR
authors: Mensenkamp
authors: Ans M W
authors: AM
authors: van den Ouweland
authors: Judith
authors: J
authors: Prins
authors: Anja
authors: A
authors: Wagner
authors: Winand N M
authors: WN
authors: Dinjens
authors: Hendrikus Jan
authors: HJ
authors: Dubbink
authors: Liselotte P
authors: LP
authors: van Hest
authors: Fred
authors: F
authors: Menko
authors: Frans
authors: F
authors: Hogervorst
authors: Senno
authors: S
authors: Verhoef
authors: Hein
authors: H
authors: te Riele
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003062:Codon / Q000235:genetics; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics* / Q000473:pathology; D003198:Computer Simulation; D053843:DNA Mismatch Repair / Q000235:genetics*; D004252:DNA Mutational Analysis; D053595:Embryonic Stem Cells / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008875:Middle Aged; D008969:Molecular Sequence Data; D051718:MutS Homolog 2 Protein / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D010375:Pedigree
chemical_list: D003062:Codon; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein
keywords: Cancer: Colon; Genetic Screening/Counselling; Lynch Syndrome; Mismatch Repair; Molecular Genetics