pediatrics
Urea Cycle Disorders
Introduction
Ureacycle disorders are characterized by hyperammonemia under catabolic or protein-loading conditions. cycle and related disorders (see the Urea Cycle and Related Disorders ) as well as many other Primaryureacycle disorders (UCDs) include carbamoyl phosphate synthase (CPS) deficiency, ornithine transcarbamylase (OTC) deficiency, argininosuccinate synthetase deficiency (citrullinemia), argininosuccinate lyase deficiency (argininosuccinic aciduria), arginase deficiency (argininemia), andN-acetylglutamate synthetase (NAGS) deficiency. The more “proximal” the enzyme deficiency is, the more severe the hyperammonemia; thus, disease severity in descending order is NAGS deficiency, CPS deficiency, OTC deficiency, citrullinemia, argininosuccinic aciduria, and argininemia. Inheritance for all UCDs is Autosomal Recessive , except for OTC deficiency, which is 