A 3-year-old boy is brought to the physician because of a 1-week history of yellowish discoloration of his eyes and skin. He has had generalized fatigue and mild shortness of breath for the past month. Three weeks ago, he was treated for a urinary tract infection with antibiotics. His father underwent a splenectomy during childhood. Examination shows pale conjunctivae and jaundice. The abdomen is soft and nontender; there is nontender splenomegaly. Laboratory studies show: Hemoglobin 9.1 g/dL Mean corpuscular volume 89 μm3 Mean corpuscular hemoglobin 32 pg/cell Mean corpuscular hemoglobin concentration 37.8% Hb/cell Leukocyte count 7800/mm3 Platelet count 245,000/mm3 Red cell distribution width 22.8% (N=13%–15%) Serum Bilirubin Total 13.8 mg/dL Direct 1.9 mg/dL Lactate dehydrogenase 450 U/L Which of the following is the most likely pathophysiology of these findings?
ADeficient glucose-6 phosphate dehydrogenase
BDecreased synthesis of alpha chains of hemoglobin
CIncreased hemoglobin S
DDecreased spectrin in the RBC membrane
EDeficiency of pyruvate kinase
A 4-month-old boy is brought to his pediatrician for a well-child visit. His parents have noticed that he has had poor growth compared to his older siblings. The boy was delivered vaginally after a normal pregnancy. His temperature is 98.8°F (37.1°C), blood pressure is 98/68 mmHg, pulse is 88/min, and respirations are 20/min. On exam, his abdomen appears protuberant, and the boy appears to have abnormally enlarged cheeks. A finger stick reveals that the patient’s fasting blood glucose is 50 mg/dL. On further laboratory testing, the patient is found to have elevated blood lactate levels, as well as no response to a glucagon stimulation test. What enzymatic defect is most likely present?
AAlpha-1,4-glucosidase
BGlycogen synthase
CAlpha-1,6-glucosidase
DGlucose-6-phosphatase
EGlycogen phosphorylase
An 11-year-old boy is brought to the emergency room with acute abdominal pain and hematuria. Past medical history is significant for malaria. On physical examination, he has jaundice and a generalized pallor. His hemoglobin is 5 g/dL, and his peripheral blood smear reveals fragmented RBC, microspherocytes, and eccentrocytes (bite cells). Which of the following reactions catalyzed by the enzyme is most likely deficient in this patient?
AGlucose-1-phosphate + UTP → UDP-glucose + pyrophosphate
BGlucose + ATP → Glucose-6-phosphate + ADP + H+
CD-glucose 6-phosphate → D-fructose-6-phosphate
DGlucose-6-phosphate + H2O → glucose + Pi
ED-glucose-6-phosphate + NADP+ → 6-phospho-D-glucono-1,5-lactone + NADPH + H+
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