Arginase-1 deficiency is a rare urea cycle disorder. The enzyme is primarily found in the liver.
Chromosome: 6q23.2
Gene: ARG1 (catalyzes the hydrolysis of arginine to ornithine and urea)
Inheritance: autosomal recessive
Infancy is typically normal, with clinical onset between 1 and 3 years of age.
Clinical findings:
(1) seizures
(2) spastic paraparesis
(3) cognitive, intellectual and developmental disabilities
(4) growth retardation
(5) hepatic fibrosis progressing to cirrhosis
(6) joint contractures
(7) microcephaly
(8) feeding difficulties with impaired nutrition
(9) episodes of encephalopathy and coma (associated with hyperammonemia)
Laboratory findings:
(1) hyperargininemia
(2) elevated serum guanidinoacetate (GAA)
(3) significantly elevated serum asymmetric dimethylarginine (ADMA)
(4) episodic hyperammonemia
(5) elevated urinary orotic acid
