Studies of erythropoietic cells in heterozygotes and homozygotes for haemoglobin Constant Spring and in heterozygotes for both haemoglobin Constant Spring and alpha-thalassaemia 1 trait: extent of globin chain precipitation and cell cycle distribution

Iron metabolism in heterozygotes for hemoglobin E (HbE), alpha-thalassemia 1, or beta-thalassemia and in compound heterozygotes for HbE/beta-thalassemia

BACKGROUND

Despite large populations carrying traits for thalassemia in countries implementing universal iron fortification, there are few data on the absorption and utilization of iron in these persons.

OBJECTIVE

We aimed to determine whether iron absorption or utilization (or both) in women heterozygous for beta-thalassemia, alpha-thalassemia 1, or hemoglobin E (HbE) differed from that in control subjects and compound HbE/beta-thalassemia heterozygotes.

DESIGN

In Thai women (n = 103), red blood cell indexes, iron status, non-transferrin-bound iron, and growth differentiation factor 15 were measured, and body iron was calculated. Fractional iron absorption was measured from meals fortified with isotopically labeled ((57)Fe) Fe sulfate, and iron utilization was measured by the infusion of ((58)Fe) Fe citrate.

RESULTS

Iron utilization was approximately 15% lower in alpha-thalassemia 1 or beta-thalassemia heterozygotes than in controls. When corrected for differences in serum ferritin, absorption was significantly higher in the alpha- and beta-thalassemia groups, but not the HbE heterozygotes, than in controls. HbE/beta-thalassemia compound heterozygotes had lower iron utilization and higher iron absorption and body iron than did controls. Nontransferrin-bound iron and growth differentiation factor 15 were higher in the compound heterozygotes, but not in the other groups, than in the controls.

CONCLUSIONS

In alpha-thalassemia 1 and beta-thalassemia heterozygotes with ineffective erythropoesis, dietary iron absorption is not adequately down-regulated, despite a modest increase in body iron stores. In populations with a high prevalence of these traits, a program of iron fortification could include monitoring for possible iron excess and for iron deficiency.

Ultrastructural characterization of the erythroid cells in a novel case of congenital anemia

Congenital dyserythropoietic anemia type I (CDA-I) is a rare genetic disease that affects erythropoiesis. On the other hand, hemoglobin H (HbH) disease is a severe form of alpha-thalassemia. We herein present ultrastructural and immunocytochemical data concerning the first reported case of congenital anemia with clinical and molecular diagnosis of HbH disease complicated by CDA-I-specific dysplasies of the erythroid cells. Fine structure and transmission electron microscope immunolabeling analysis of the bone marrow and peripheral blood samples were consistent with a potential co-existence of the two defects in the same patient, producing a novel and diagnostically important dyserythropoietic profile. In the patient under investigation both nuclear and plasma membrane of the erythroid cells are almost equally defective. The unknown defect causes the concomitant precipitation of beta- and alpha-globin chains (or hemoglobin), along with an unidentified protein(s). The unusual inclusions gain access to the euchromatin area and exhibit higher affinity for the plasma membrane than the classic inclusions of precipitated alpha- or beta-globin chains seen in thalassemia. The affected erythroid precursors are presented with severe nuclear distortions, endonuclear globin loads, morphological evidence of apoptosis and increased erythrophagocytosis. Plasma membrane distortions and the rate of protein precipitation were aggravated with differentiation. Our findings provide additional evidence for a specific activation of a beta-thalassemic-like mechanism in CDA-I, containing not only the hemoglobin biosynthesis as previously suggested, and interpret the prototypal hematological portrait, which is an HbH disease, modified and partially counterbalanced by the effect of CDA-I or an unidentified CDA-I-like disease. The reported data describe the complexity of the interactions between the CDA-I and the HbH disease, revealing essential pathogenic events of the novel anemia and, indirectly, of the CDA-I.