For the millions living with mental retardation, this breakthrough holds out a ray of hope. An international group of researchers, including two Bangalore neuroscientists, has identified an enzyme that causes the syndrome called Fragile X and successfully reverses its symptoms in mice.

Fragile X Syndrome is a genetic condition caused by a defect in the X chromosome. It's the chief cause of mental retardation, and in some cases, a known cause of autism. It can cause varying degrees of impairment, from minor learning problems to cognitive disability. Until now, there's been no known treatment for Fragile X.

Bangalore, was published in the 'Proceedings of the National Academy of Sciences' on Monday. Scientists say we can expect similar results in human beings in five years.

"We found that a specific enzyme in the brain called P21-Activated Kinase (PAK), when inhibited, reversed the debilitating symptoms of Fragile X in mice," said Sumantra Chatterji of the National Centre for Biological Sciences.

The second researcher, Shankaranarayana Rao of NIMHANS, explained that in the brain, connections between neurons are formed by protrusions called 'spines'. The Indian contribution to the research involved monitoring how these spines were altered in the mentally challenged.