NAGS and citrullinemia type I: There are six types of urea cycle disorder: N-acetylglutamate synthase deficiency; carbamoyl phosphate synthetase-1 deficiency; ornithine carbamoyltransferase deficiency; argininosuccinic acid synthetase deficiency (citrullinemia); argininosuccinase acid lyase deficiency (argininosuccinic aciduria); and arginase deficiency (argininemia) [31].