ARG1 variants cause hyperargininemia

ARG1 is a cytosolic enzyme that is highly expressed in the liver and expressed at a lower level in the kidney. It catalyzes the final step of the urea cycle, the conversion of L-arginine to urea and L-ornithine (Di Costanzo et al, 2005). Arginase 1 deficiency, also known as argininemia (OMIM 207800) is an autosomal recessive inborn error of metabolism that is characterized by elevated arginine levels and leads to spastic paraparesis, neurological and developmental delays. Unlike other urea cycle defects, hyperammonemia is not a common manifestation of arginase 1 deficiency (reviewed in Diez-Fernandez et al, 2018).

Summary from Reactome (R-HSA-9956514), read 2026-09-23.