Adenylosuccinate lyase deficiency

Adenylosuccinate lyase deficiency is a rare autosomal recessive metabolic disorder of purine synthesis. It is recognised biochemically by the appearance in cerebrospinal fluid and urine of two succinylpurines, succinylaminoimidazolecarboxamide riboside (SAICA riboside) and succinyladenosine (S-Ado). These are the dephosphorylated forms of the two substrates of the enzyme adenylosuccinate lyase (ADSL), which acts in the de novo pathway of purine biosynthesis. ADSL catalyses two separate reactions in making purine nucleotides, each of which removes fumarate by beta-elimination, producing aminoimidazole carboxamide ribotide (AICAR) from SAICAR in one and adenosine monophosphate (AMP) from S-AMP in the other.