A 6-month-old male presents with recurrent vomiting, irritability, and poor weight gain over 2 months. Vital signs show HR 128/min, RR 26/min, temp 37.2°C, and BP 85/55 mmHg. Physical examination reveals brittle hair and mild hepatomegaly; no rash noted. Laboratory studies demonstrate ammonia 156 μmol/L (normal <50), and plasma amino acid analysis shows elevated argininosuccinate. Serum transaminases are normal. Which enzyme deficiency best explains these findings?
- A)Phenylalanine hydroxylase
- B)Argininosuccinate lyaseGABARITO
- C)Methionine synthase
- D)Ornithine transcarbamylase
- E)Arginase
Explicação
This child has argininosuccinate lyase deficiency, a urea cycle disorder in which argininosuccinate cannot be cleaved to arginine and fumarate. Hyperammonemia produces episodic vomiting and irritability, and brittle hair can occur due to arginine deficiency. E... Ver explicação completa e trilha adaptativa →