Highly homologous loci on the X and Y chromosomes are hot-spots for ectopic recombinations leading to XX maleness

Nat Genet. 1994 Jul;7(3):414-9. doi: 10.1038/ng0794-414.


In 80% of XX males, maleness is due to the presence of Y-specific DNA including the SRY gene and results from an abnormal terminal X-Y interchange during paternal meiosis. Here we address the molecular basis of this ectopic recombination through the analysis of the X-Y junction in two class 3 XX males. We show that each of the rearrangements has involved X-Y highly homologous loci on the sex-specific part of these chromosomes (98.7% and 96% sequence identity over 1.2 and 1.1 kb respectively). Moreover in five out of six other XX males, the X-Y junctions are located in the same rearranged restriction fragment as in either of these patients. These fragments thus define two hot-spots of ectopic recombination which together could account for about one third of XX males. Evolution of these loci in primates is discussed.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Biological Evolution
  • Crossing Over, Genetic*
  • DNA, Satellite / genetics
  • DNA-Binding Proteins / genetics*
  • Humans
  • Male
  • Molecular Sequence Data
  • Nuclear Proteins*
  • Primates / genetics
  • Repetitive Sequences, Nucleic Acid
  • Sequence Alignment
  • Sequence Homology, Nucleic Acid*
  • Sex Chromosome Aberrations / genetics*
  • Sex Determination Analysis*
  • Sex-Determining Region Y Protein
  • Transcription Factors*
  • X Chromosome* / ultrastructure
  • Y Chromosome* / ultrastructure


  • DNA, Satellite
  • DNA-Binding Proteins
  • Nuclear Proteins
  • SRY protein, human
  • Sex-Determining Region Y Protein
  • Transcription Factors

Associated data

  • GENBANK/X70410
  • GENBANK/X70411
  • GENBANK/X70412
  • GENBANK/X70413