Adenylosuccinate lyase, also known as ADSL, is an enzyme that converts adenylosuccinate to AMP and fumarate as part of the purine nucleotide cycle. Defects in ADSL are the cause of adenylosuccinase deficiency (ADSL deficiency). ADSL deficiency is an autosomal recessive disorder characterized by the accumulation in the body fluids of succinylaminoimidazole-carboxamide riboside (SAICA-riboside) and succinyladenosine (S-Ado).