The DNA sequence of the human X chromosome

Nature. 2005 Mar 17;434(7031):325-37. doi: 10.1038/nature03440.


The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Neoplasm / genetics
  • Centromere / genetics
  • Chromosomes, Human, X / genetics*
  • Chromosomes, Human, Y / genetics
  • Contig Mapping
  • Crossing Over, Genetic / genetics
  • Dosage Compensation, Genetic
  • Evolution, Molecular*
  • Female
  • Genetic Linkage / genetics
  • Genetics, Medical
  • Genomics*
  • Humans
  • Male
  • Polymorphism, Single Nucleotide / genetics
  • RNA / genetics
  • Repetitive Sequences, Nucleic Acid / genetics
  • Sequence Analysis, DNA*
  • Sequence Homology, Nucleic Acid
  • Testis / metabolism


  • Antigens, Neoplasm
  • RNA