The lack of mitochondrial ornithine results in reduced ornithine transcarbamylase (OTC) activity, which slows down the urea cycle, leading to accumulation of carbamoyl-phosphate and hyperammonemia. Carbamoyl-phosphate either forms orotic acid through the pyrimidine pathway or binds with lysine to produce homocitrulline explaining the homocitrullinuria. Here, OTC is linked to Hyperammonemia.