Hemolytic Anemias of Childhood

A 3-year-old boy from South India presents with jaundice, pallor, and hepatosplenomegaly. His mother reports recurrent episodes of dark urine and abdominal pain over the past 6 months. On examination, he is icteric with a palpable spleen 4 cm below the costal margin. Laboratory investigations show: Hemoglobin 7.2 g/dL, reticulocyte count 12%, indirect bilirubin 4.8 mg/dL, direct bilirubin 0.6 mg/dL, LDH 680 U/L, haptoglobin <10 mg/dL. Peripheral blood smear reveals spherocytes and polychromasia. Osmotic fragility test is positive. What is the most likely diagnosis?

A 2-year-old girl from rural Maharashtra presents to the emergency department with severe pallor, jaundice, and dark-colored urine following a 3-day febrile illness. Her mother reports that the child had been given antimalarial medication (sulfamethoxazole-trimethoprim) 5 days ago. On examination: HR 140/min, RR 38/min, temperature 38.5°C, hepatosplenomegaly present. Laboratory results: Hemoglobin 5.8 g/dL, reticulocyte count 18%, indirect bilirubin 6.2 mg/dL, LDH 1200 U/L, haptoglobin <5 mg/dL, creatinine 1.8 mg/dL (baseline normal). Peripheral blood smear shows polychromasia, bite cells, and Heinz bodies. Direct antiglobulin test (DAT) is negative. What is the most likely diagnosis?

Which of the following enzymes is deficient in glucose-6-phosphate dehydrogenase (G6PD) deficiency?

In hereditary spherocytosis, which membrane protein defect is most commonly responsible for the loss of biconcave shape and increased osmotic fragility?