Erythrocyte lipids and vitamin E in type II congenital dyserythropoietic anemia

HEMPAS. Hereditary erythroblastic multinuclearity with positive acidified serum lysis test

Congenital dyserythropoietic anemia type II or HEMPAS (hereditary erythroblastic multinuclearity with positive acidified serum lysis test) is a genetic anemia in humans caused by a glycosylation deficiency. Erythrocyte membrane glycoproteins, such as band 3 and band 4.5, which are normally glycosylated with polylactosamines lack these carbohydrates in HEMPAS. Polylactosamines accumulate as glycolipids in HEMPAS erythrocytes. Analysis of N-glycans from HEMPAS erythrocyte membranes revealed a series of incompletely processed N-glycan structures, indicating defective glycosylation at N-acetylglucosaminyltransferase II (GnT-II) and/or alpha-mannosidase II (MII) steps. Genetic analysis has identified two cases from England in which the MII gene is defective. Mutant mice in which the MII gene was inactivated by homologous recombination resulted in a HEMPAS-like phenotype. On the other hand, linkage analysis of HEMPAS cases from southern Italy excluded MII and GnT-II as the causative gene, but identified a gene on chromosome 20q11. HEMPAS is therefore genetically heterogeneous. Regardless of which gene is defective, HEMPAS is characterized by incomplete processing of N-glycans. The study of HEMPAS will identify hitherto unknown factors affecting N-glycan synthesis.

Acquired iron-deficiency anaemia due to impaired iron transport

A previously healthy 39-year-old woman presented with severe iron-deficiency anaemia, but she had lost no blood and her serum iron level was high. Her bone marrow was hypercellular with a predominance of erythroid elements and had no stainable iron deposits, but it also showed dyserythropoiesis and an excess of apparently normal plasma cells. IgM was demonstrated on her bone-marrow erythrocytes and their precursors. On azathioprine and prednisone therapy she had a complete clinical and haematological remission. The impaired iron transport and the associated dyserythropoiesis were probably due to an IgM-mediated autoimmune process. Diabetes mellitus, which first appeared during her anaemic illness, could also have been due to an autoimmune process. This is the first report of an iron-deficiency anaemia caused by a naturally acquired impairment of iron transport.

Type I congenital dyserythropoietic anaemia with myelopoietic abnormalities and hand malformations

Type I dyserythropoietic anaemia was diagnosed in an infant, who presented with respiratory distress and hepatosplenomegaly soon after birth. Anaemia became manifest during the neonatal period. The case clearly proves the congenital nature of the disease. Abnormalities of the myelopoietic series indicate that it might be a stem cell disease and the presence of skeletal anomalies of the hands suggests a genetic relationship to some cases of Fanconi and Diamond anaemia. No serum lipid or vitamin E deficiency was present as in type II congenital dyserythropoietic anaemia. Serial serum ferritin determinations indicated that iron stores are increased early in type I congenital dyserythropoietic anaemia despite no transfusion load.

Lipid peroxidation in the hemolytic uremic syndrome

Based on recent evidence of a genetic influence on prognosis (1) and the existence of red cell membrane phospholipid depletion with low or absent serum alpha-tocopherol (2) levels in three children with the Hemolytic Uremic Syndrome (H.U.S.), we wish to suggest the existence of an inborn error of antioxident capacity as the basic pathogenetic mechanism in the development of the hemolytic uremic syndrome (H.U.S.).

The anemia of vitamin E deficiency in swine: an experimental model of the human congenital dyserythropoietic anemias

The ultrastructural and erythrokinetic characteristics of vitamin E deficiency in swine were investigated in an effort to evaluate the suitability of the swine disorder as a model of the human congenital dyserythropoietic anemias. The dominant erythrokinetic abnormality in vitamin E deficient pigs, as in the CDAs, is ineffective erythropoiesis. As in some patients with CDA, the activity of a number of erythrocyte enzymes was increased. Distinctive ultrastructual changes previously described in patients with CDA were found in normoblasts from vitamin E deficient pigs. The morphologic, erythrokinetic, biochemical and ultrastructural similarities between vitamin E deficiency in swine and the CDAs in man appear to justify the study of the animal disorder as a model of the human disease. A complete hematologic response was elicited by the administration not only of vitamin E, but also, as in the previous studies of vitamin E deficiency in monkeys, by hexahydrocoenzyme Q4. The partial hematologic response occurring after deletion of tocopherol stripped corn oil from the diet indicates that factors other than the dietary lack of vitamin E are important in the pathogenesis of this disorder.

Congenital dyserythropoietic anaemia with features of both type I and TYPE II

A 13 year old girl with the typical clinical and haematological picture of congenital dyserythropoietic anaemia (CDA) is reported. The bone marrow is highly cellular with 70 per cent erythroid cells, and 28% bi- and multinuclear cells among the orthochromatic and polychromatic erythroblasts. Moderate megaloblastoid changes are present. On light microscopy the findings are in agreement with those described in CDA type II. On electron microscopy both the cytoplasmatic changes described as typical of CDA type II, and the nuclear changes found in type I can be demonstrated. The acidified serum test (Ham test) is negative with normal sera. The patient's red blood cells show increased agglutinability with anti-I and and anti-I antibodies, but no haemolysis. Total serum lipids are about 50% of the normal average. All lipoprotein classes are lowered to about the same extent. The total phospholipid content of the erythrocytes is slightly reduced, with a moderate, relative increase of the lecithin fraction and a decrease of the sphingomyelin fraction. Doubts can be raised about the tenability of the current classification of CDA based on morphological and serological criteria, especially about the distinction between types I and II.