A 22 year old Greek man presents with rapid anemia and jaundice following treatment of malaria. He is noted to have Heinz bodies. Choose the single most likely cause from the given options?

The key is A. G6PD deficiency. [G6PD (glucose-6-phosphate dehydrogenase) deficiency exacerbated by administration of oxidant drugs (e.g., primaquine, dapsone, quinidine). In active G6PD deficiency, Heinz bodies can be seen in red blood cells on a blood film].