New Clue Found for Fragile X Syndrome-Epilepsy Link

Fragile X syndrome is the most common form of inherited intellectual disability. Patients with FXS usually have a hyperexcitable nervous system, which causes anxiety, hyperactivity, increased sensory activity and about 20% of all patients with FXS develop epilepsy. Until recently, the causes have been unknown. Researchers have found variables that may contribute to the relationship between epilepsy and FXS. Patients with FXS are missing the FMRP protein. This gene regulates the production of a protein that controls electrical signals in the brain. In patients missing FMRP, the brain decreases production of a protein called Kv4.2. FMRP controls many genes, by acting as a stopping mechanism. It impedes with the step where RNA is made into protein. So in FMRP’s deficiency, there is a heightened protein production in synapses at the junctions between brain cells, where chemical communication takes place. However, protein Kv4.2 is different. Instead of producing more in FMRP’s absence, there is decreased production. This protein is an ion channel, and when neurons are stimulated it allows for the electrical charge to flow out of them. Kv4.2 is the major ion channel that regulates the excitability of neurons in the hippocampus. This region of the brain is important for learning and memorization. When there is a mutation of the gene that encodes Kv4.2, there result can be temporal lobe epilepsy. Testing done in laboratories suggest that drugs that decrease glutamate signaling could partly restore levels of Kv4.2, leading to reduced hyperexcitability in patients with FXS.

My student lecture assignment last semester was Fragile X Syndrome, and I think it’s great that research is still occurring and new theories are being made for this genetic syndrome. This affects approximately 1 in 3600 males and 1 in 4000 to 6000 females, and is the leading cause of inherited intellectual disability, so it’s important that progress is being made.

http://www.sciencedaily.com/releases/2011/04/110412171202.htm