title: Common variants in mismatch repair genes associated with increased risk of sperm DNA damage and male infertility.
abstract: BACKGROUND
  The mismatch repair (MMR) pathway plays an important role in the maintenance of the genome integrity, meiotic recombination and gametogenesis. This study investigated whether genetic variations in MMR genes are associated with an increased risk of sperm DNA damage and male infertility.
  
  
  METHODS
  We selected and genotyped 21 tagging single nucleotide polymorphisms (SNPs) in five MMR genes (MLH1, MLH3, PMS2, MSH4 and MSH5) using the SNPstream 12-plex platform in a case-control study of 1,292 idiopathic infertility patients and 480 fertile controls in a Chinese population. Sperm DNA damage levels were detected with the Tdt-mediated dUTP nick end labelling (TUNEL) assay in 450 cases. Fluorescence resonance energy transfer (FRET) and co-immunoprecipitation techniques were employed to determine the effects of functional variants.
  
  
  RESULTS
  One intronic SNP in MLH1 (rs4647269) and two non-synonymous SNPs in PMS2 (rs1059060, Ser775Asn) and MSH5 (rs2075789, Pro29Ser) seem to be risk factors for the development of azoospermia or oligozoospermia. Meanwhile, we also identified a possible contribution of PMS2 rs1059060 to the risk of male infertility with normal sperm count. Among patients with normal sperm count, MLH1 rs4647269 and PMS2 rs1059060 were associated with increased sperm DNA damage. Functional analysis revealed that the PMS2 rs1059060 can affect the interactions between MLH1 and PMS2.
  
  
  CONCLUSIONS
  Our results provide evidence supporting the involvement of genetic polymorphisms in MMR genes in the aetiology of male infertility.
authors.affiliation: State Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing 210029, China. aihuagu@njmu.edu.cn
authors.forename: Guixiang
authors.initials: G
authors.lastname: Ji
authors.forename: Yan
authors.initials: Y
authors.lastname: Long
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Cong
authors.initials: C
authors.lastname: Huang
authors.forename: Aihua
authors.initials: A
authors.lastname: Gu
authors.forename: Xinru
authors.initials: X
authors.lastname: Wang
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D047369:Chromatin Immunoprecipitation; D004249:DNA Damage; D053843:DNA Mismatch Repair; D045643:DNA Repair Enzymes / Q000235:genetics*; D031541:Fluorescence Resonance Energy Transfer; D020022:Genetic Predisposition to Disease; D006801:Humans; D020287:In Situ Nick-End Labeling; D007248:Infertility, Male / Q000453:epidemiology* / Q000235:genetics*; D008297:Male; D020641:Polymorphism, Single Nucleotide; D018570:Risk Assessment; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D045643:DNA Repair Enzymes