X chromosome

Researchers have found nine new genes on the X-chromosome that, when knocked out, lead to learning disabilities. An international team of researchers, from more than 70 countries, studied almost all X chromosome genes in 208 families with learning disabilities and found approximately 1-2% of X chromosome genes, when knocked out, have no apparent effect on an individual’s ability to function in the ordinary world. Learning disability is significantly more common in males than in females and genetic causes have long been sought on the X chromosome: males have only one X chromosome and so a gene mutation on the X is more likely to have an effect in males than in females.