GCDH and Other metabolic disease: Pharmacological inhibition of E1a has been proposed as a strategy for substrate reduction therapy to treat glutaric aciduria type 1 (GA1: MIM 231670), a metabolic disorder that is caused by mutations in the GCDH gene encoding the mitochondrial protein glutaryl-CoA dehydrogenase (GCDH; EC 1.3.8.6) located downstream of E1a in the L-lysine degradation pathway (Scheme 1) [15].