RHEOLOGICAL PROPERTIES OF ERYTHROCYTES IN PATIENTS WITH CONGENITAL DYSERYTHROPOETIC ANEMIA II

Abstract

The aetiology of congenital dyserythropoetic anemia (CDA) II is unknown. The diagnosis is based on morphologic and immunologic criteria. We present three girls with well docomented CDA II who were followed for 5 to 8 years. The anemia was always mild and the body iron status (assessed by serum ferritin, serum iron and transferrin) was normal. In none of the girls was splenectomy indicated. Morphologic features of erythrocytes and bone marrow erythoid cells were studied by means of light and electron microscopy. 15-30% of the erythrocytes showed invaginations with endocytic cysterns and shape abnormalities (echinocytosis, anisocytosis, microcytosis). Erythrocyte deformation and aggregation were studied in the three patients by means of rheoscope techniques. Erythrocytes with abnormal shape showed significantly decrease deformability, particularly at low shear stress. At low shear stress, up to 15% of erythrocytes did not deform at all. At high shear stress, both shape abnormalities and erythrocyte rigidity were less pronounced. Erythrocyte aggregation studied under standard conditions was slightly increased. This agrees with previous findings of decreased neraminic acid in erythrocyte membrane of these patients. Our studies indicate that both decreased erythrocyte deformability and increased erythrocyte aggregation may contribute to the shortened life span of erythrocytes in patients with dyserythropoetic anemia type II.