Congenital Dyserythropoietic Anemia Type II is a rare form of congenital anemia but is the most common of the congenital dyserythropoietic anemias. It is also referred to as HEMPAS (hereditary erythroblastic multinuclearity with positive acidified serum lysis test).
Chromosome: 20p11.23
Gene: SEC23B
Inheritance: autosomal recessive
Clinical features:
(1) mild to moderate anemia present from birth
(2) hemolysis with jaundice
(3) ineffective erythropoiesis with reticulocytopenia
(4) splenomegaly
(5) iron overload
A few patients may become transfusion-dependent if anemia is severe enough. Splenectomy may reduce the anemia and decrease the need for transfusion.
A bone marrow biopsy may show binuclearity in erythroblasts.
Red blood cells are lysed by acidified sera of 40-60% of healthy adults due to the presence of a naturally occurring cold-reacting IgM antibody (anti-i).
Criteria for diagnosis (Heimpel et al):
(1) all of the following:
(1a) congenital anemia with jaundice
(1b) ineffective erythropoiesis
(1c) at least 10% of red cell precursors are binucleate
(2) one or more of the following:
(2a) positive acid lysis test
(2b) typical abnormality of bands 3 and 4.5 in SDS-PAGE
(2c) double membrane running internally from the cell membrane of late erythroblasts on electron microscopy
Complications may include:
(1) hepatic cirrhosis
(2) heart failure
(3) diabetes mellitus
(4) hypothyroidism
(5) hypogonadism
