However, the formation of the hydroxylated metabolites could cause serious side effects, such as methemoglobinemia and hemolytic anemia in patients with deficiency in glucose-6-phosphate dehydrogenase (G6PD) activity [9], and hence the use of primaquine clinically is discouraged, especially in Southeast Asia where G6PD deficiency is prevalent. Here, G6PD is linked to hyperinsulinemic hypoglycemia, familial, 4.