Fig. 4
From: Corticospinal tract damage in HHH syndrome: a metabolic cause of hereditary spastic paraplegia
Urea cycle and related pathways. The illustration shows the biochemical pathways connecting HHH syndrome, argininemia and pyrroline-5-carboxylate synthetase deficiency (gray boxes), the three disorders of aminoacid metabolism related to the distal part of the urea cycle sharing phenotypic similarities. AGAT, l-arginine:glycine amidinotransferase; ASL, argininosuccinate lyase; ASS, argininosuccinate synthetase; CPS, carbamyl-phosphate synthetase; GAA, guanidinoacetate; GAMT, guanidinoacetate N-methyltransferase; OAT, ornithine aminotransferase; ODC, ornithine decarboxylase; ORNT1, ornithine/citrulline antiporter; OTC, ornithine transcarbamylase; P5C, pyrroline-5-carboxylate; P5CR, pyrroline-5-carboxylate reductase; P5CS, pyrroline-5-carboxylate synthase