This gene encodes one of several forms of glutamic acid decarboxylase, identified as a major autoantigen in insulin-dependent diabetes.The enzyme encoded is responsible for catalyzing the production of gamma-aminobutyric acid from L-glutamic acid.A pathogenic role for this enzyme has been identified in the human pancreas since it has been identified as an autoantigen and an autoreactive T cell target in insulin-dependent diabetes.This gene may also play a role in the stiff man syndrome.Deficiency in this enzyme has been shown to lead to pyridoxine dependency with seizures.Alternative splicing of this gene results in two products, the predominant 67-kD form and a less-frequent 25-kD form.[provided by RefSeq]