Individuals with a proximal urea cycle disorder, such as carbamoyl phosphate synthetase
deficiency 1 or ornithine transcarbamylase deficiency, may present with encephalopathy
resulting from hyperammonemia. The clinical presentation of arginase deficiency is
considerably different, characterized by progressive spasticity involving the lower extremities
and usually dementia. Diagnosis may be delayed, and patients are often thought to have
cerebral palsy. The true etiology of brain injury in arginase deficiency is unknown, but is not …