arginase deficiency

Pathology

• urea cycle disorder
• arginase mediates terminal step in urea cycle

Genetics

• autosomal recessive
• defect in arginase-1

Clinical manifestations

• typical presentation as older infant
• delayed development
• protein intolerance
• occasional episodes of vomiting & somnolence without apparent cause
• spastic diplegia

Laboratory

• plasma ammonia: hyperammonemia is rarely observed
• urine arginine generally not massive
• serum arginine may not be greatly increased with restriction of protein intake

Differential diagnosis

• argininosuccinate lyase deficiency
• methylmalonic acidemia
• carbamoyl phosphate synthetase deficiency
• N-Acetylglutamate synthetase deficiency
• citrullinemia
• ornithine transcarbamylase deficiency
• hyperammonemia
• propionic acidemia (propionyl CoA carboxylase deficiency)
• hyperammonemia-hyperornithinemia-homocitrullinemia syndrome
• hyperinsulinemia
• cerebral palsy

Management

• low protein diet
• oral sodium benzoate or sodium phenylbutyrate
• consults
  • medical geneticist
  • metabolic disease specialist
  • dietitian

More general terms

• urea cycle disorder

Additional terms

• arginase-1 (hepatic arginase, ARG1)