Washington: New genetic clues have been found in fragile X syndrome, which is the most common cause of inherited intellectual disability and seizures, by studying the case of a person.
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 behavioral, neurological and physical symptoms, but this patient had only a single error in this gene and exhibited only two classic traits of fragile X, allowing the researchers at Washington University to parse out a previously unknown role for the gene.
Co-senior author Vitaly A. Klyachko said that this individual case has allowed them to separate two independent functions of the fragile X protein in the brain and by finding the mutation, even in just one patient, and linking it to a partial set of traits, they have identified a distinct function that this gene is responsible for and that is likely impaired in all people with fragile X.
The new study suggests that fragile X, which results from an inherited genetic error in a gene called FMR1 and the error prevents the manufacture of a protein called FMRP, likely also causes overactive transmitters that send out too much information.
Klyachko added that the mechanisms that researchers have long thought were the entirety of the problem with fragile X are obviously still very much in play, but this unique case has allowed them to see that something else is going on.
The finding also raises the possibility that drugs recently tested as treatments for fragile X may be ineffective, at least in part, because they only dialed down the brain's receivers, presumably leaving transmitters on overdrive.
The researchers said they can't rule out the possibility that additional problems also are caused by this mutation and are present in fragile X, but this research specifies at least one additional dysfunction not previously recognized. Further studies of patients with different partial symptoms of fragile X and different mutations, if any can be found, might identify more.
The research is published online in the Proceedings of the National Academy of Sciences (PNAS).