Following a relatively normal early developmental period, a 6-month-old boy becomes pale and lethargic and begins to show signs of deteriorating motor skill. The infant has severe megaloblastic anemia; however, serum measurements of iron, folate, vitamins B₁₂, and B₆ demonstrate they are within normal range. Urine samples were clear when fresh, but when left to stand for several hours showed an abundant white precipitate that was composed of fine needle-shaped crystals. Analysis of the crystals identified them as orotic acid. Significant clinical improvement would be expected to be observed in this infant following oral administration of which of the following compounds?

Question

Quizplus · Accepted Answer

The infant likely has orotic aciduria, a disorder of pyrimidine metabolism. Uridine supplementation bypasses the metabolic block and improves symptoms.

Following a Relatively Normal Early Developmental Period, a 6-Month-Old Boy