After the identification of the locus for CDA II, also known as HEMPAS (hereditary erythroblast multinuclearity with positive acidified serum test), on the long arm of chromosome 20 (20q11.2) we have analyzed by a mutational search seven candidate genes in a large series of CDA II patients.
This review deals with clinical, diagnostic, and biochemical aspects of all characterized CDGs, including a disorder affecting the N-glycosylation of erythrocytes, congenital dyserythropoietic anemia type II (CDA II/HEMPAS), and the first disorders affecting O-glycosylation.
Type II congenital dyserythropoietic anaemia (CDA-II or HEMPAS) is an autosomal recessive disorder, representing the most frequent form of congenital dyserythropoiesis.
Three main types of CDA have been distinguished: CDA I and CDA III, whose loci have been already mapped, and CDA II (MIM 224100), the most frequent among CDAs, which is transmitted as an autosomal recessive trait and is known also as "HEMPAS" (hereditary erythroblast multinuclearity with positive acidified serum).