Neonatal Screening — IEM

A 7-day-old male neonate, born to non-consanguineous parents in Delhi, presents with poor feeding, lethargy, and vomiting since day 5 of life. Antenatal and delivery history were unremarkable. On examination, the baby is hypotonic with a characteristic 'musty' or 'mousy' odour on the breath. Neonatal screening blood spot shows elevated phenylalanine (>20 mg/dL; normal <2 mg/dL) and normal tyrosine. Urine ferric chloride test is positive (green colour). What is the most likely diagnosis?

In phenylketonuria, the enzyme deficiency results in accumulation of which metabolite that causes the characteristic 'musty' or 'mousy' odor in urine and sweat?

Which of the following inborn errors of metabolism is NOT routinely screened in the Indian national neonatal screening program?

A 10-day-old female neonate born in Mumbai presents with poor feeding, irritability, and seizures since day 8 of life. Mother reports the baby was feeding well until day 5. On examination, the infant is hypertonic with exaggerated reflexes and opisthotonus. Blood gas shows metabolic acidosis (pH 7.18, HCO₃⁻ 12 mEq/L). Plasma amino acids show markedly elevated branched-chain amino acids (leucine 8.5 mg/dL, isoleucine 4.2 mg/dL, valine 6.1 mg/dL; normal <3 mg/dL each) and elevated alloisoleucine. Urine has a characteristic maple syrup odour. What is the most likely diagnosis and the most appropriate immediate management?