A 6-month-old boy admitted with failure to thrive with high glutamine and Uracil in urine. Hypoglycemia, high blood ammonia. Treatment given for 2 months. At 8 months again admitted for failure to gain weight. Gastric tube feeding was not tolerated. Child became comatose. Parenteral Dextrose given. Child recovered from coma within 24 hours. What is the enzyme defect?

Ans. B. Ornithine transcarbamoylaseIn the given case clue to diagnosis are:High Glutamine: Usually seen in hyperammonemia. Because glutamine is the transport form of ammonia from brain and most other tissues. So in hyperammonemia Glutamine level is elevated.Increased uracil in urine can be seen in Ornithine Transcarbamoylase defect because as OTC defective, carbamoyl phosphate in mitochondria spills to cytoplasm. Then it enter into Pyrimidine synthesis. Pyrimidine intermediates and pyrimidines can accumulate. Hence Uracil in urine.