is a rare, inherited metabolic condition that results from a lack of the enzyme adenylosuccinate lyase. Signs and symptoms vary greatly from person to person. In general, affected individuals may have a mix of neurological symptoms, which usually includes abnormalities with cognition and movement, autistic features, epilepsy, muscle wasting, and feeding problems. Although less common, abnormal physical features can include severe growth failure, small head, abnormally shaped head, strabismus, small nose with upturned nostrils, thin upper lip, and low set ears. Adenylosuccinase deficiency is caused by mutations in the ADSL gene and is inherited in an autosomal recessive fashion. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.