A team of US scientists has gained new insight into fragile X syndrome - the most common cause of inherited intellectual disability.
In patients with fragile X, a key gene is completely disabled, eliminating a protein that regulates electrical signals in the brain and causing a host of behavioural, neurological and physical symptoms.
The patient in the study, in contrast, had only a single error in this gene and exhibited only two classic traits of fragile X - intellectual disability and seizures - allowing the researchers to parse out a previously unknown role for the gene.
"This individual case has allowed us to separate two independent functions of the fragile X protein in the brain," said Vitaly A Klyachko, associate professor at Washington University's school of medicine.
By finding the mutation, even in just one patient, and linking it to a partial set of traits, we have identified a distinct function that this gene is responsible for and that is likely impaired in all people with fragile X, he added.
The finding also raises the possibility that drugs recently tested as treatments for fragile X may be ineffective.
The research appeared in the journal Proceedings of the National Academy of Sciences (PNAS).
