The GCDH gene encodes a mitochondrial enzyme called glutaryl-CoA dehydrogenase, which catalyzes the oxidative decarboxylation of glutaryl-CoA to crotonyl-CoA in the degradative pathway of L-lysine, L-hydroxylysine, and L-tryptophan metabolism.

Defects in the glutaryl-CoA dehydrogenase enzyme are the cause of an autosomal recessive metabolic disorder called glutaric acidemia type I. This condition is characterized by progressive dystonia and athetosis due to gliosis and neuronal loss in the basal ganglia.