To which of the following diseases is pyruvate kinase deficiency most similar clinically?

Both pyruvate kinase deficiency and glucose-6-phosphate dehydrogenase deficiency are red cell enzyme deficiencies characterized clinically by long "normal" periods interspersed with episodes of hemolytic anemia triggered by infections and oxidant drug injury (antimalarial drugs, sulfonamides, nitrofurans). In both of these conditions, the cell morphology between hemolytic episodes is usually normal or close to normal. The alpha and beta thalassemias, in their major forms, are characterized by persistent severe anemia. In the trait forms, they are characterized by mild anemia. Hereditary spherocytosis is characterized by intermittent hemolysis, but, unlike pyruvate kinase deficiency and glucose-6-phosphate dehydrogenase deficiency, oxidant drugs are not a specific trigger for hemolysis. Ref: Van Solinge W.W., van Wijk R. (2010). Chapter 46. Disorders of Red Cells Resulting from Enzyme Abnormalities. In J.T. Prchal, K. Kaushansky, M.A. Lichtman, T.J. Kipps, U. Seligsohn (Eds), Williams Hematology, 8e.