Glutaric Aciduria type I (GA1) (OMIM #231670) is an autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism characterised by a deficiency of glutaryl-CoA dehydrogenase (EC 1.3.8.6), an enzyme encoded by the GCDH (OMIM #608801) gene, resulting in elevations of glutaric acid and 3-hydroxyglutaric acid (Figure 2b). This evidence concerns the gene GCDH and glutaryl-CoA dehydrogenase deficiency.