FIRST US CASE OF ADENYLOSUCCINATE LYASE DEFICIENCY WITH SEVERE HYPOTONIA

Addenylosuccinate lyase (ASL) deficiency is a defect in purine de novo synthesis pathway, The disease has variable clinical presentation inv olving psychomotor retardation, seizures, hypotonia, and autism. The p resence of succinyladenosine and succinylamino-imidazole carboxamide r iboside (SAICA riboside) in body fluids characterizes the biochemical phenotype. All cases of ASL deficiency described to date have been dia gnosed in Europe, Using a high-resolution thin-layer chromatography (T LC) technique combining screening for ASL deficiency and disorders of saccharide metabolism, me found the first case of this disease in the US. The patient presented with delayed motor development and profound hypotonia. The family history and routine laboratory tests were negati ve, Screening for metabolic disorders detected the presence of succiny ladenosine and SAICA riboside in urine, The activity of ASL in the pat ient's skin fibroblasts was 43% of controls (patient, mean = 1.20 nmol /min/mg of protein, s = 0.21, n = 3; controls, mean = 2.75 nmol/min/mg of protein, s = 0.61, n = 7), In a 15-month-old girl with profound hy potonia, we established the diagnosis of ASL deficiency by demonstrati ng succinyladenosine and SAICA riboside in urine and decreased residua l activity of ASL in skin fibroblasts. (C) 1997 by Elsevier Science In c.