system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 2-month-old boy is brought to the physician by his mother because of poor weight gain and irritability since delivery. He is at the 10th percentile for height and below the 5th percentile for weight. Physical examination shows conjunctival pallor. Laboratory studies show:
Hemoglobin 11.2 g/dL
Mean corpuscular hemoglobin 24.2 pg/cell
Mean corpuscular volume 108 μm3
Serum
Ammonia 26 μmol/L (N=11–35 μmol/L)
A peripheral blood smear shows macrocytosis of erythrocytes and hypersegmented neutrophils. Supplementation with folate and cobalamin is begun. Two months later, his hemoglobin concentration is 11.1 g/dL and mean corpuscular volume is 107 μm3. The patient's condition is most likely caused by failure of which of the following enzymatic reactions?"
assistant
Orotate to uridine 5'-monophosphate