CHAMPAIGN, Ill. - Efforts to understand the mechanism for the most common cause of genetically inherited mental impairment in males have been bolstered by researchers who have found that the synthesis of a key protein occurs in an unexpected location in the brain.
Scientists from four universities report that the fragile X protein is produced in synapses junctions through which nerve cells communicate. The discovery is backed by a second study that shows when the gene that initially receives the fragile X protein is "knocked out" of the X chromosome, halting the protein's production within synapses, then normal brain development appears to stop at an early stage.
Findings of the studies conducted at the University of Illinois will appear in the May 13 Proceedings of the National Academy of Sciences. The research was funded primarily by the National Institute of Mental Health and the FRAXA Research Foundation, a non-profit organization run by parents and medical professionals.
"The fragile X protein that is produced at synapses appears to be essential to normal synapse maturation and development of the wiring diagram of the brain," said lead researcher William T. Greenough of the U. of I. psychology department and the U. of I. Beckman Institute for Advanced Science and Technology.
There is no cure for fragile X syndrome, which is caused by the genetic inability to normally produce the fragile X protein. "Fragile X" refers to the broken appearance of the X chromosome -- half the chromosome pair that determines sex -- when cells are cultured under specific conditions. The gene was found in 1969, but its relationship to mental retardation was not understood. It was sequenced and named the Fragile X Mental Retardation Gene in 1991, but its mechanisms remained a mystery.
The Fragile X Mental Retardation Gene is carried by mothers and passed
on to sons. One in every 1,000 women is believed to carry the defective
gene; about one
Contact: Jim Barlow
University of Illinois at Urbana-Champaign