title: Knobbed acrosome defect is associated with a region containing the genes STK17b and HECW2 on porcine chromosome 15.
abstract: BACKGROUND
  Male infertility is an increasing problem in all domestic species including man. Localization and identification of genes involved in defects causing male infertility provide valuable information of specific events in sperm development. Correct condensation of the sperm head and development of the acrosome are required for fertile sperm. In the Finnish Yorkshire pig population a knobbed acrosome defect (KAD) has been reported which appears to be of genetic origin. In previous studies we have shown that a large number of affected spermatozoa have a cystic swelling anterior to the apical part of the acrosome.
  
  
  RESULTS
  Characterization of the knobbed acrosome affected sperm revealed that both the acrosomal granules and chromatin are affected. This type of KAD appears to be a previously unknown and serious form of the defect. A genome wide scan with PorcineSNP60 Genotyping BeadChip defined the KAD associated region within 0.7 Mbp on porcine chromosome 15. Two genes, STK17b and HECW2, located within this region were sequenced. The expression of these genes appeared comparable in KA-affected and control boars. The known function of HECW2 in acrosome development highlighted this gene as a good candidate responsible for the KAD. One nonsynonymous SNP was identified within the HECW2 gene. However, as this mutation was found in homozygous state in individuals with normal sperm, this is not likely to be the causal mutation.
  
  
  CONCLUSIONS
  In this study we identified two candidate genes for a severe defect affecting both the sperm acrosome and chromatin that causes infertility. One of these genes, HECW2, plays an important role in ubiquitination, a prerequisite for chromatin remodelling and acrosome formation, highlighting the involvement of this gene in the knobbed acrosome defect and male infertility.
authors.affiliation: Agrifood Research Finland, MTT, Biotechnology and Food Research, Genomics, FI-36100 Jokioinen, Finland. anu.sironen@mtt.fi
authors.forename: Anu
authors.initials: A
authors.lastname: Sironen
authors.forename: Pekka
authors.initials: P
authors.lastname: Uimari
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Nagy
authors.forename: Sándor
authors.initials: S
authors.lastname: Paku
authors.forename: Magnus
authors.initials: M
authors.lastname: Andersson
authors.forename: Johanna
authors.initials: J
authors.lastname: Vilkki
mesh_terms: D000177:Acrosome / Q000201:enzymology* / Q000473:pathology* / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D033481:Chromosomes, Mammalian / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006239:Haplotypes / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D034421:Sus scrofa / Q000235:genetics*
chemical_list: D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D017346:Protein Serine-Threonine Kinases