Inborn Errors Of Metabolism Practice Test

A 14-month-old infant is evaluated for developmental delay and failure to thrive. Laboratory results show markedly elevated plasma homocysteine levels but low methionine levels. A complete blood count reveals megaloblastic anemia. The patient improves with supplementation of methylcobalamin.

A 9-month-old infant presents with failure to thrive, progressive loss of motor skills, and an enlarged abdomen. Physical examination reveals significant hepatosplenomegaly and a cherry-red spot on the macula. A bone marrow biopsy shows lipid-laden macrophages with a 'foamy' appearance.