What is Arginase 1 Deficiency?

Arginase 1 Deficiency (ARG1-D) is a rare, progressive, inherited disease that typically presents in childhood. It is an inherited disorder that affects children, teens and adults, and may significantly impact a patient’s health over time.

ARG1-D is characterized by complete or partial lack of the enzyme arginase in the liver and red blood cells. Arginase is one of six enzymes that play a role in the breakdown and removal of nitrogen from the body, a process known as the urea cycle. The lack of the arginase enzyme results in excessive accumulation of nitrogen, in the form of ammonia (hyperammonemia), in the blood and arginine (hyperarginemia) in the blood and cerebrospinal fluid. Untreated children may exhibit seizures, spasticity, short stature and intellectual disability. Arginase 1 deficiency is inherited as an autosomal recessive genetic disorder.

Those affected with ARG1-D experience persistently high levels of an amino acid called arginine, which leads to muscle tightness (spasticity), missed developmental milestones, intellectual disability, seizures and early death.