Periodic acid-schiff-positive megaloblasts in pernicious anemia.

Periodic acid-Schiff-positive material representing glycogen was found in bone marrow megaloblasts at all stages of maturation from 11 patients with severe untreated pernicious anemia. This accumulation of glycogen in megaloblasts, which are known to have disordered biosynthesis of DNA, RNA, and histones, suggests that carbohydrate metabolism may also be abnormal in vitamin B12 deficiency, perhaps as a result of an abnormality in the enzyme amylophosphorylase.