Symptoms in the neonatal type of this disorder are similar to those of ornithine transcarbamylase deficiency, carbamoyl phosphate synthetase deficiency or citrullinaemia. There is poor feeding, persistent vomiting and lethargy, leading to coma and death in untreated patients. Argininosuccinic acid, usually detected after conversion to its anhydrides, is present in excess in the urine. In later onset types there is failure to thrive and feeding difficulties in the first few months, or developmental delay and convulsions in the second year. Abnormally fragile hair (trichorrhexis nodosa) is often present in these patients.
Enzyme Tests: [14C]-citrulline incorporation in cultured fibroblasts is measured to diagnose this disorder.