Hemoglobinopathies (sickle cell disease, thalassemia, and hemoglobin defects)Red cell membrane disorders (e.g., hereditary spherocytosis, paroxysmal nocturnal hemoglobinuria, and hereditary elliptocytosis)Red cell enzyme defects (glucose-6-phosphate dehydrogenase or pyruvate kinase deficiencies). Here, G6PD is linked to paroxysmal nocturnal hemoglobinuria.