Gene conversion between the X chromosome and the male-specific region of the Y chromosome at a translocation hotspot

Am J Hum Genet. 2009 Jul;85(1):130-4. doi: 10.1016/j.ajhg.2009.06.009. Epub 2009 Jul 2.


Outside the pseudoautosomal regions, the mammalian sex chromosomes are thought to have been genetically isolated for up to 350 million years. However, in humans pathogenic XY translocations occur in XY-homologous (gametologous) regions, causing sex-reversal and infertility. Gene conversion might accompany recombination intermediates that resolve without translocation and persist in the population. We resequenced X and Y copies of a translocation hotspot adjacent to the PRKX and PRKY genes and found evidence of historical exchange between the male-specific region of the human Y and the X in patchy flanking gene-conversion tracts on both chromosomes. The rate of X-to-Y conversion (per base per generation) is four to five orders of magnitude more rapid than the rate of Y-chromosomal base-substitution mutation, and given assumptions about the recombination history of the X locus, tract lengths have an overall average length of approximately 100 bp. Sequence exchange outside the pseudoautosomal regions could play a role in protecting the Y-linked copies of gametologous genes from degeneration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosomes, Human, X*
  • Chromosomes, Human, Y*
  • Continental Population Groups / genetics
  • Gene Conversion*
  • Humans
  • Male
  • Molecular Sequence Data
  • Protein-Serine-Threonine Kinases / genetics
  • Translocation, Genetic*


  • PRKX protein, human
  • PRKY protein, human
  • Protein-Serine-Threonine Kinases

Associated data

  • GDB/GQ281268
  • GDB/GQ281269
  • GDB/GQ281270
  • GDB/GQ281271
  • GDB/GQ281272
  • GDB/GQ281273
  • GENBANK/GQ281274
  • GENBANK/GQ281275