A high density of X-linked genes for general cognitive ability: a run-away process shaping human evolution?

Trends Genet. 2001 Dec;17(12):697-701. doi: 10.1016/s0168-9525(01)02446-5.


The incidence of mental disability is 30% higher in males than in females. We have examined entries in the OMIM database that are associated with mental disability and for several other common defects. Our findings indicate that compared with the autosomes, the X chromosome contains a significantly higher number of genes that, when mutated, cause mental impairment. We propose that these genes are involved in the development of cognitive abilities and thus exert a large X-chromosome effect on general intelligence in humans. We discuss these conclusions with regard to the conservation of the vertebrate X-chromosomal linkage group and to human evolution.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Brain / metabolism
  • Cognition Disorders / genetics
  • Cognition*
  • Conserved Sequence
  • Evolution, Molecular*
  • Female
  • Fertility
  • Gene Frequency
  • Genes
  • Genetic Linkage*
  • Haplotypes
  • Humans
  • Intellectual Disability / genetics*
  • Intelligence / genetics*
  • Male
  • Models, Genetic
  • Mutation
  • Selection, Genetic
  • Testis / physiology
  • X Chromosome*