Mental Retardation Gene Mutation Found

British scientists have identified a gene mutation that causes X-linked mental retardation for which there was no previously known molecular diagnosis.

F. Lucy Raymond of the University of Cambridge and Patrick Tarpey of the Wellcome Trust Sanger Institute described the gene ZDHHC9, found in those with severe retardation, as being mutated to the point of entirely losing function.

X-linked mental retardation is severe, with the condition running in families and only affecting male offspring.

The researchers collected genetic samples from 250 families in which at least two boys had mental retardation. They then analyzed the X chromosome for gene mutations.

We have identified the cause of problems in certain families and are able to tell whether or not women are carriers of the condition, Raymond said. Consequently, the families that had previously chosen to forego having children because there was no method of testing can now be tested.

The study appears in the current issue of The American Journal of Human Genetics.