Nine New X Chromosome Genes Linked to Learning Disabilities in Males

An international team of 70 researchers have now determined nine new genes on the X chromosome which lead to learning disabilities if knocked out. The team studied nearly all X chromosome genes in as many as 208 families with these disabilities, in what was the largest screen of this sort ever reported. 720 out of the approximately 800 known genes on the X chromosome were sequenced. It is estimated that the prevalence of learning disability is 2 to 3 per cent and is much more common in males than females. This is obviously because it is more likely for a gene mutation to occur on the X chromosome of males, as they only have one X chromosome compared to females, who have two.

As well as these new gene discoveries, there was another significant finding which stunned researchers. This was that approximately one to two per cent of X chromosome protein coding genes have no effect on an individual in any respect, when knocked out. Geneticists have already said that further research is needed in this area due to the effect this finding will have on following studies. From now onwards researchers must be wary of the fact that just because a knocked out gene in an individual with a particular disease is present, does not mean that this gene is the causal factor of the disease.

The next step now is to implement this improved knowledge of the complex of genes in clinical practise. Genetic counselling is already offered to families with learning disabilities. However, these new findings will improve the provision of diagnostics to families and allow for more comprehensive genetic counselling, which will allow family members to make more efficient decisions. Although improved treatments in this area are waiting to be developed, information this research can bring will provide support to effected families. Families will also be able to make better informed reproductive choices.


Reference:
Wellcome Trust Sanger Institute (2009, April 20). Learning Disabilities In Males: Nine New X Chromosome Genes Linked To Learning Disabilities. ScienceDaily. Retrieved April 22, 2009, from http://www.sciencedaily.com­ /releases/2009/04/090419133841.htm