title: Array-based DNA methylation profiling in male infertility reveals allele-specific DNA methylation in PIWIL1 and PIWIL2.
abstract: OBJECTIVE
  To identify CpG sites differentially methylated in peripheral blood of men with idiopathic infertility due to impaired spermatogenesis as compared with fertile controls.
  
  
  METHODS
  DNA methylation profiling on peripheral blood samples using the HumanMethylation450 BeadChip (Illumina) in patients and controls, single-nucleotide polymorphism (SNP) typing by Sanger sequencing.
  
  
  METHODS
  University institute in cooperation with genetic and infertility clinics.
  
  
  METHODS
  30 infertile men with normal CFTR and AZF tests and karyotype, and 10 fertile male controls.
  
  
  METHODS
  None.
  
  
  METHODS
  DNA methylation levels at CpG sites.
  
  
  RESULTS
  We identified 471 CpGs (287 genes) as differentially methylated between patients and controls. These were significantly enriched for the gene ontology functions MHC class II receptor activity and piwi-interacting (piRNA) binding. The latter was associated with two methylation-sensitive SNPs in the genes PIWIL1 and PIWIL2, respectively, which showed significant allele distribution skewing in the infertile cohort. We found that 445 (94.5%) of 471 differentially methylated CpGs were associated with SNPs, but 26 (15 genes) were not genomically templated, including the ENO1, MTA2, BRSK2, and LBX2 genes previously associated with fertility and spermatogenesis.
  
  
  CONCLUSIONS
  Our study identifies surrogate DNA methylation markers for idiopathic infertility in peripheral blood and suggests that allele-specific DNA methylation differences at regulatory sites of genes involved in piRNA regulation are associated with disturbed spermatogenesis.
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Carolin
authors: C
authors: Friemel
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Ole
authors: O
authors: Ammerpohl
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Jana
authors: J
authors: Gutwein
authors: Department of Gynecology and Obstetrics, Center of Reproductive Medicine, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Andreas G
authors: AG
authors: Schmutzler
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Almuth
authors: A
authors: Caliebe
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Monika
authors: M
authors: Kautza
authors: Department of Gynecology and Obstetrics, Center of Reproductive Medicine, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Sören
authors: S
authors: von Otte
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors: Reiner
authors: R
authors: Siebert
authors: Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany. Electronic address: sbens@medgen.uni-kiel.de.
authors: Susanne
authors: S
authors: Bens
mesh_terms: D000328:Adult; D060565:Argonaute Proteins / Q000235:genetics*; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D005787:Gene Frequency; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000453:epidemiology* / Q000235:genetics*; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007248:Infertility, Male / Q000453:epidemiology* / Q000235:genetics*; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis / Q000706:statistics & numerical data; D015995:Prevalence; D013091:Spermatogenesis / Q000235:genetics*
chemical_list: D060565:Argonaute Proteins; D005819:Genetic Markers; C421088:PIWIL1 protein, human; C486868:PIWIL2 protein, human
keywords: DNA methylation; HLA; PIWIL1; PIWIL2; male infertility