Gamma-aminobutyric acid transaminase deficiency

Gamma-aminobutyric acid transaminase (GABA-T) deficiency is an extremely rare disorder that has only been reported in 5 patients in 3 families. This condition involves a problem with a substance called GABA-T, which plays an important role in slowing down the activity of cells in the brain. In GABA-T deficiency, there is a lack of GABA-T, which causes a substance GABA to build up in the nervous tissue, including our spinal cord and brain. When GABA is in excess in our cells, there is increased signaling between cells in the nervous system, which leads to several different symptoms. The major symptoms include slowing of thought and activity, low muscle tone, being tired, and having seizures. This disorder normally occurs at a young age and may even start before birth. Often, the condition is so severe that individuals affected do not survive past infancy.

GABA-T deficiency involves the ABAT gene. In individuals with GABA-T deficiency, there are changes in the ABAT gene which cause less GABA-T to be made. This condition is passed down from parent to child in an autosomal recessive manner, which means one mutation from each parent is needed to cause symptoms. A person with only one mutation is called a carrier because they “carry” one changed copy and one unchanged copy of the gene. Carriers also show no signs or symptoms of the condition. If both parents are carriers, each of their children has a one in four chance (25%) of having the condition and a 50/50 chance of being a carrier.

Treatment varies based on the case. If you or a family member has been diagnosed with GABA-T deficiency, talk with your doctor about the most current treatment options. Support groups are also good resources of support and information.