Arginase 1 deficiency: long-term follow-up of the original patients

Arginase 1, the enzyme responsible for the last step of the urea cycle, catalyzes the hydolysis of arginine to urea and ornithine. In contrast to other urea cycle defects, its deficiency usually does not cause early and catastrophic hyperammonemia. Instead, this extremely rare disease typically presents with progressive cerebral and motoneuron disorder (spastic paraplegia and seizures) and/or a hepatic phenotype with neonatal cholestasis, acute liver failure, or liver fibrosis, making it a prime example of how pathology in the liver affects other organs. The underlying pathogenetic mechanisms have not been fully…