 Mutated adenylosuccinate lyase (ASL) causes clinical disease in patients that is referred to as adenylosuccinate lyase deficiency.This condition is rare, and it presents with varying degrees of psychomotor retardation, autism, muscle wasting, and epilepsy.The exact cause of disease is unknown, but possibilities include not enough purine nucleotide synthesis for cell replication, malfunctioning of the purine nucleotide cycle, and a buildup of substrates to toxic levels.