Glucose 6-phosphate dehydrogenase (G6PD) deficiency, an X-linked disorder, is the most common enzymatic disorder of red blood cells in humans, affecting 200 to 400 million people worldwide [1,2].
The diagnosis and treatment of G6PD deficiency will be discussed here. The genetics, pathophysiology, and clinical manifestations of G6PD deficiency are reviewed separately. (See "Genetics and pathophysiology of glucose-6-phosphate dehydrogenase deficiency" and "Clinical manifestations of glucose-6-phosphate dehydrogenase deficiency".)
The clinical expression of glucose 6-phosphate dehydrogenase (G6PD) deficiency encompasses a spectrum of hemolytic syndromes. While affected patients are usually asymptomatic, some have episodic anemia while a few have chronic hemolysis. With the most prevalent G6PD variants (G6PD A- and G6PD Mediterranean), severe hemolysis is induced by the sudden destruction of older, more deficient erythrocytes after exposure to drugs having a high redox potential (including the antimalarial drug primaquine and certain sulfa drugs) or to fava beans, selected infections, or metabolic abnormalities. (See "Clinical manifestations of glucose-6-phosphate dehydrogenase deficiency".)
The likelihood of developing hemolysis and the severity of disease are determined by the magnitude of the enzyme deficiency, which in turn is determined by biochemical characteristics of the G6PD variant. The World Health Organization has classified the different G6PD variants according to the magnitude of the enzyme deficiency and the severity of hemolysis . Classes IV and V are of no clinical significance. (See "Genetics and pathophysiology of glucose-6-phosphate dehydrogenase deficiency", section on 'Classification of G6PD variants'.)
●Class I variants have severe enzyme deficiency (less than 10 percent of normal) and have chronic hemolytic anemia