HEMPAS: Congenital Dyserythropoietic Anaemia (Type II)

Abstract

HEMPAS or ‘CDA Type II’ is an autosomal recessive form of congenital dyserythropoietic anaemia, characterized by ineffective erythropoiesis. The clinical and haematological features of 39 patients are reviewed. Anaemia and jaundice are characteristic; less than a quarter of the patients are sufficiently anaemic to need repeated transfusions. The spleen is usually moderately to markedly enlarged and the liver is often slightly enlarged. The bone marrow is strikingly abnormal, with many erythroblasts containing two or more nuclei. The circulating red cells show moderate morphological abnormalities; unlike normal cells, they are strongly agglutinated by anti-i, and lysed by anti-i and anti-I. Moreover, the red cells are agglutinated and lysed by an alloantibody present in many normal sera, but they are not lysed in the patient's own serum. It seems possible that an abnormality of the cell membrane may be the cause of the defective cell division, the failure of the multinucleated erythroblasts to expel their nuclei, and the characteristic serological reactions.