GABA-transaminase (GABA-T) deficiency is a very rare disorder caused by mutations in the ABAT gene. Only a small number of affected individuals (about 15) have been reported.
Figure 1: Geographical Distribution of GABA-T Deficiency Patients
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell has mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
The disorder is characterized by weak muscle tone, uncontrolled limb movements, exaggerated reflexes, recurrent seizures, and excessive sleepiness. Affected babies may grow faster in length than usual, even though they have feeding problems and may not gain weight as quickly as expected. Most children do not achieve normal developmental milestones of infancy, such as sitting unassisted. In the past, reports suggested mortality in the first 2 years of life. However, recent reports indicate survival into adolescence and adulthood. We are still learning more about GABA-T deficiency.