A child was born at home and developed seizures 2 days after birth. Upon examination in the ER it was found that the infant had elevated serum NH₄⁺, glutamate, and alanine. The ER physician suspected that the child was suffering from a defect in the urea cycle and ordered a urinalysis to assess the level of orotic acid and the serum was assayed for the level of citrulline. Orotic acid levels were above normal and citrulline was barely detectable. A defect in which enzyme of the urea cycle would most likely account for the symptoms observed in this infant?

Question

Quizplus · Accepted Answer

The elevated orotic acid and low citrulline levels suggest a defect in ornithine transcarbamoylase (OTC), which leads to accumulation of carbamoyl phosphate that is converted to orotic acid.

A Child Was Born at Home and Developed Seizures 2