Identification of a Y chromosome haplogroup associated with reduced sperm counts

Hum Mol Genet. 2001 Sep 1;10(18):1873-7. doi: 10.1093/hmg/10.18.1873.


In man, infertility is associated with microdeletions of specific regions of the long arm of the Y chromosome. This indicates that factors encoded by the Y chromosome are necessary for spermatogenesis. However, the majority of men with either idiopathic azoospermia or oligozoospermia have grossly intact Y chromosomes and the underlying causes of their infertility are unknown. We hypothesized that some of these individuals may carry other rearrangements or sequence variants on the non-recombining region of the Y chromosome that may be associated with reduced spermatogenesis. To test this hypothesis, we typed the Y chromosome in a group of Danish men with known sperm counts and compared the haplotype distribution with that of a group of unselected Danish males. We found that one class of Y chromosome, referred to as haplogroup 26+, was significantly overrepresented (27.9%; P < 0.001) in the group of men with either idiopathic oligozoospermia (defined as <20 x 10(6 )sperm/ml) or azoospermia compared to the control Danish male population (4.6%). This study defines, for the first time, a class of Y chromosome that is at risk for infertility in a European population. This observation suggests that selection may be indeed active on the Y chromosome, at least in the Danish population, raising the possibility that it could alter the pattern of Y chromosome haplotype distribution in the general population.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Evolution, Molecular
  • Follicle Stimulating Hormone / blood
  • Genetic Markers
  • Haplotypes / genetics*
  • Humans
  • Infertility, Male / genetics
  • Inhibins / blood
  • Luteinizing Hormone / blood
  • Male
  • Oligospermia / genetics
  • Phylogeny
  • Polymorphism, Genetic
  • Semen / cytology
  • Sex Hormone-Binding Globulin / metabolism
  • Sperm Count*
  • Y Chromosome / genetics*


  • Genetic Markers
  • Sex Hormone-Binding Globulin
  • inhibin B
  • Inhibins
  • Luteinizing Hormone
  • Follicle Stimulating Hormone