Haemoglobinopathies Including Thalassaemia

Asia Pacific Society of Human Genetics (APSHG) from conception to 2019: 13 years of collaboration to tackle congenital malformation and genetic disorders in Asia

Putting together the reports in this issue that come from a representation of the different countries in Asia presents an opportunity to share the unique story of the Asia Pacific Society of Human Genetics (APSHG), which has provided the authors of many of these articles. This paper, authored by the Past Presidents of the Society, shares glimpses of how medical genetics activities were first organized in the Asia Pacific region and provides interesting corollaries on how under-developed and developing countries in this part of the world had developed a unique network for exchange and sharing of expertise and resources. Although APSHG was formally registered as a Society in Singapore in 2006, the Society has its origins as far back as in the 1990s with members from different countries meeting informally, exchanging ideas, and collaborating. This treatise documents the story of the experiences of the Society and hopes it will provide inspiration on how members of a genetics community can foster and build a thriving environment to promote this field.

Elevated erythropoietin and cytokines levels are related to impaired reticulocyte maturation in thalassemic patients

Serum EPO concentration is related primarily to the rate of erythrocyte production and, under the stimulation of hypoxia, increases exponentially as hemoglobin (Hb) decreased. The level of EPO was determined in 141 subjects including 43 normal, 44 thalassemic patients and 54 thalassemic trait subjects. The EPO level was significantly higher in the thalassemic patients (54.8mU/ml in HbH disease [α thal1/α thal2;], 78.1mU/ml in HbH with Hb CS [α thal 1/CS]; 95.6mU/ml in β-thal/HbE splenectomized [BE(S)]; and 114.8mU/ml in β-thal/HbE non-splenectomized [BE(NS)]as compared with 12.0mU/ml in normal subjects. No significant differences were detected in thalassemic trait subjects. In addition, the levels of EPO in thalassemic patients is correlated significantly with the number of reticulocytes and the reticulocyte fractions especially the fraction of immature reticulocytes. Interestingly, the highest level of EPO/% retic ratio as indicated for EPO non-responder was detected in BE(NS) patients. However, the impaired reticulocytes maturation was found to be related significantly with the levels of TNF-α,IFN-γ,IL-10, and VEGF. Since, TNF-α, IFN-γ, IL-10 and VEGF are reported as the cytokines with erythropoietic inhibitory mediators, the variation of these cytokines in thalassemic environments may be associated to the anemic crisis in these patients.

New updating into hemoglobinopathies

Thalassemia and abnormal hemoglobin are the most common genetic disorders and are considered health problems in many developing countries. In the last few years, there has been much progress in laboratory diagnosis, treatment and control of thalassemia. The variation in the clinical severity in both α- and β-thalassemia reflects a genotype-phenotype interaction. This is important for future therapeutic intervention and should be well characterized in each population. The quality of life of the patients is much improved with regular blood transfusion and novel iron chelators. The cure for thalassemia is possible by stem cell transplantation and future gene therapy. It is expected that under multinational collaboration the prevention of thalassemia will happen worldwide.

The thalassemias and related disorders

The thalassemias, sickle cell disease, and other hemoglobinopathies represent a major group of inherited disorders of hemoglobin synthesis. The abnormal hemoglobins were reviewed in the July 2006 issue of Baylor University Medical Center Proceedings. Because of immigration patterns and population flow, these disorders are becoming increasingly more prevalent in the USA. In this article, the clinical aspects of the more common thalassemia syndromes are reviewed. For most symptomatic patients with thalassemia, there is no definite cure; only supportive management of the anemia is possible. A very limited number of patients with thalassemia may be cured by bone marrow transplantation from HLA-identical donors. Other tentative approaches to management include stimulation of fetal hemoglobin synthesis and attempts at somatic cell gene therapy. Prevention of disease transmission by carrier screening programs along with prenatal diagnosis remain of paramount importance in the reduction of these diseases worldwide.

Chicken Egg Yolk Antibodies Specific for the γ Chain of Human Hemoglobin for Diagnosis of Thalassemia

Immunoglobulin Y (IgY) technology was used to generate anti-hemoglobin Bart's (Hb Bart's) IgY antibodies (Abs) for development into an enzyme-linked immunosorbent assay (ELISA) test for thalassemia diagnosis. Hb Bart's purified from the hemolysate of a patient with Hb Bart's hydrops fetalis (homozygous alpha-thalassemia) was used to immunize a chicken via the pectoralis muscle. After water dilution and sodium sulfate precipitation, 40 to 70 mg of IgY could be extracted from an egg. IgY, first detected in sera 2 weeks after immunization, reached the highest titer at week 4, and the titer remained stable for at least 2 weeks before declining. The pattern of Ab response in the yolk was the same as in the serum but was somewhat delayed. The IgY Abs produced reacted with gamma globin, Hb Bart's, Hb F, normal cord hemolysate (Hbs F plus A), and Hb Bart's hydrops fetalis (Hbs Bart's plus Portland) and to a lesser degree with beta globin, Hb A, Hb A2 and adult hemolysate (Hbs A plus A2), but the Abs did not react with alpha globin. Immunoaffinity purification with Hb A coupled to Sepharose was used to isolate an unbound IgY that reacted with Hb F, Hb Bart's, and gamma globin, and this IgY was used to develop an ELISA test for thalassemia diagnosis. The results of direct ELISA analyses of 336 hemolysate samples from individuals with various known thalassemia genotypes and phenotypes and from healthy individuals confirmed the specificity of the polyclonal Abs for Hbs containing Hb F and Hb Bart's. This specificity, which was due to the Abs' strong reactivity in cases of pathologic thalassemic diseases and weak reactivity in cases of nonpathologic thalassemic diseases, depended on the levels of Hb Bart's and Hb F.

Prevalence and Clinical Significance of Hepatitis C Virus Infection in Thai Patients with Thalassemia

Hepatitis C virus (HCV) infection is a common cause of liver disease in thalassemia major patients in Western, especially Mediterranean, countries. Its significance in thalassemic patients from Southeast Asia has not been critically evaluated. In this report, we describe our study of the prevalence of HCV infection among Thai patients with thalassemia. The relationships of the infection to blood transfusion and the infection's effects on liver function have also been determined. Of the 104 patients studied, 21 (20.2%) tested positively by enzyme immunoassay for anti-HCV antibody, whereas only 2 patients (2%) had the hepatitis B surface antigen. There was no significant relationship between the presence of anti-HCV antibodies and the number and frequency of blood transfusions. In fact, 2 patients (10%) who tested positive for anti-HCV antibodies had never received transfusions. Patients with anti-HCV antibodies had significantly abnormal liver functions, such as higher levels of serum aspartate aminotransferase (SGOT) and alanine aminotransferase (SGPT) and lower levels of serum albumin, compared with patients without anti-HCV antibodies (P = .021, .017, and .004, respectively). However, there were also significant correlations between iron status as indicated by transferrin saturation or serum ferritin levels and SGOT, SGPT, and gamma-glutamyltransferase (GGT) levels. Moreover, abnormal liver function as represented by elevated levels of SGOT, SGPT, GGT, and serum alkaline phosphatase was observed more frequently in patients with iron overload than in patients with a lower degree of iron burden. The presence of HCV did not alter the effects of iron overload on liver function. The findings suggest that both HCV and iron overload are the main causes of abnormal liver function in Thai patients with thalassemia. The treatment of both problems, if coexisting in patients with thalassemia, is required to prevent progression to chronic liver disease.

Pulmonary arterial hypertension in previously splenectomized patients with beta-thalassemic disorders

Our aim was to study the cause and describe the clinical features of pulmonary arterial hypertension (PHT) in splenectomized beta-thalassemia (beta-Thal) patients. Ten splenectomized beta-Thal patients with systolic pulmonary artery (PA) pressure >30 mm Hg were evaluated by echocardiography, right-heart catheterization, and pulmonary angiography. Five of these patients later underwent hemodynamic studies. Echocardiography and pulmonary angiography on the 10 patients showed normal values of left ventricular systolic function and no findings of acute or chronic pulmonary embolism. Hemodynamic evaluation showed very high PA pressures associated with markedly increased pulmonary vascular resistance indices (PVRIs). Hematological evaluation of the 10 patients showed marked anemia, markedly increased numbers of nucleated red blood cells (nRBCs), and serum ferritin. Mean platelet count, plasma beta2 thromboglobulin, and thrombin-antithrombin III complex levels were significantly increased. It was concluded that PHT can be found in splenectomized beta-Thal patients. Features associated with PHT were female sex, hemoglobin E/beta-Thal, status many years postsplenectomy, marked anemia, markedly increased nRBC count, thrombocytosis, and very high serum ferritin levels. PHT was not due to pulmonary emboli. Our findings suggested that severe PHT was due to increased PVRI from thrombotic pulmonary arteriopathy, likely from chronic low-grade hypercoagulability and platelet activation after splenectomy.

Relationship between hypercoagulable state and erythrocyte phosphatidylserine exposure in splenectomized haemoglobin E/beta-thalassaemic patients

Small pulmonary arterial thromboses can occur following splenectomy of patients with haemoglobin E/beta-thalassaemia (Hb E/beta-thal). We compared plasma markers of coagulation activation in vivo and red blood cell (RBC) markers of procoagulant activity in 15 Hb E/beta-thal patients who were not splenectomized (NS), 15 who had been splenectomized (S), and 15 normal controls (NC). Levels of plasma thrombin-antithrombin III complex (TAT) were significantly higher in the S group than in either the NS or the NC groups, and levels of prothrombin fragment 1.2 (F 1.2) were significantly higher in the S than in the NC group. Diluted Russell's viper venom clotting times were significantly shorter when RBCs from group S patients were added to the assay compared with RBCs from the NC group. Phosphatidylserine (PS) expression (% of annexin V-positive RBCs) on the outer leaflet of RBC membrane of both 'larger'- and 'smaller'-sized RBCs was significantly higher for the S than the NC group. The RBC PS expression of the S and the NS groups, respectively, accounted for 25 x 3% (P = 0 x 174) and 6.3% (P = 0 x 675) of the variation in plasma TAT levels. Our findings indicated that, when compared with NC, splenectomized patients with Hb E/beta-thal were in a chronic low-grade hypercoagulable state associated with increased numbers of circulating PS exposed RBCs. This condition may have a role in the risk of these patients for pulmonary arterial thromboses.

Major hematologic diseases in the developing world- new aspects of diagnosis and management of thalassemia, malarial anemia, and acute leukemia

The three presentations in this session encompass clinical, pathophysiological and therapeutic aspects of hematologic diseases which impact most heavily on developing world countries. Dr. Victor Gordeuk discusses new insights regarding the multi-faceted pathogenesis of anemia in the complicated malaria occurring in Africa. He describes recent investigations indicating the possible contribution of immune dysregulation to this serious complication and the implications of these findings for disease management. Dr. Surapol Issaragrisil and colleagues describe epidemiologic and clinical characteristics of the thalassemic syndromes. In addition to being considered a major health problem in Southeast Asia, the migration throughout the world of people from this region has caused the disease to have global impact. A unique thalassemia variant, Hb Ebeta-thalassemia, with distinctive clinical features, has particular relevance for this demographic issue. Special focus will be reported regarding recent prenatal molecular screening methods in Thailand which have proven useful for early disease detection and disease control strategies. Dr. Raul Ribeiro describes a clinical model for providing effective treatment for a complex malignancy (childhood acute lymphoblastic leukemia) in countries with limited resources. With the multidisciplinary approach in Central American of the joint venture between St. Jude Children's Research Hospital International Outreach Program and indigenous health care personnel, major therapeutic advances for this disease have been achieved. Given the major demographic population shifts occurring worldwide, these illnesses also have important clinical implications globally. These contributions demonstrate that lessons learned within countries of disease prevalence aid our understanding and management of a number of disorders prominently seen in developed countries. They will show how effective partnerships between hematologists in more and less developed nations may work together to produce important advances for treating major hematologic diseases in less developed regions. A major focus relates to the socio-economic and medical burden of these diseases in developing countries with limited resources. As such, these problems provide a challenge and an opportunity for collaborative interaction between hematologists and policy makers worldwide.

Hematopoietic progenitor cells in the blood and bone marrow in various hematologic disorders

Hematopoietic progenitor cells are present in the blood and the bone marrow. Changes in the numbers of hematopoietic progenitor cells reflect alteration of pluripotent stem cells. We discuss such changes in common hematologic diseases including aplastic anemia, paroxysmal nocturnal hemoglobinuria (PNH) and thalassemia. In aplastic anemia, the numbers of burst forming units-erythroid (BFU-E) and colony-forming units-granulocyte-macrophage (CFU-GM) are much decreased; the decrease still exists after recovery from therapy. In PNH, the numbers of progenitor cells are low, even in the presence of marrow hypercellularity. In thalassemia, the numbers of progenitor cells are much increased; more pronounced in splenectomized patients.

Hematologic disorders in children from southeast Asia

The overall laboratory features of the common RBC disorders occurring in Southeast Asians is summarized in Table 4. These erythrocyte disorders will continue to be important public health issues, and it has been predicted that most new cases of thalassemia in the United States will occur in this population group. The fertility rate in Southeast Asian families is very high, with an average of more than five children delivered by each married woman. This number of children is consistent with perceptions of ideal family size, and, to date, no evidence suggests any change in the size of Southeast Asian families who now reside in the United States. Moreover, attitudes about health care, reasons why one seeks medical attention, and a variety of other cultural issues may impair the effectiveness of genetic counseling and other preventive measures designed to reduce the incidence of serious blood diseases. Genetic screening and prenatal diagnosis clearly have led to a markedly decreased incidence of homozygous thalassemia disorders in high-risk Mediterranean populations throughout the world. With further assimilation into Western culture, a similar disease may occur in the Southeast Asian population also.

Lymphocytes in beta-thalassemia/HbE: subpopulations and mitogen responses

Lymphocyte subpopulations and proliferative responses to mitogens of 24 beta-thalassemia/HbE patients were studied and compared with those of 23 healthy controls. Results of the study were analyzed in correlation with clinical aspects i.e. severity of disease (anemia), frequency of infections and iron status. T(CD3+) lymphocytes were found to increase in thalassemic patients compared to normal controls. The CD4+ or CD8-positive lymphocytes and CD4/CD8 ratio were not statistically different from normals. Without mitogen, lymphocytes from thalassemic patients incorporated more [3H]Tdr than those from normal controls. Stimulation index (SI) of these cells after various mitogens were lower than in normal subjects. The observations were more obvious in patients with severe disease (severe anemia) and those who had frequent infections. These findings suggest that lymphocytes from thalassemic patients are activated in vivo. Whether these cells are less efficient in response to new or previously unexposed antigens remains to be proven.

Collection of cord blood stem cells for transplantation in thalassemic patients

Thalassemia is widely distributed throughout the world and is one of the major public health problems. The use of bone marrow transplantation, the only curative therapy for thalassemia, is limited because less than 30% of the patients have unaffected and HLA-identical siblings as donors. Cord blood stem cells, an alternative source of stem cells for transplantation, have been successfully transplanted into patients with several diseases after myeloablative therapy. Twenty cord blood samples from unaffected neonates whose siblings had severe thalassemia were collected. The median volume was 80 ml. The median number of cells and colony forming units-granulocyte-macrophage in cord blood was 9.2 x 10(8) and 3.4 x 10(5), respectively. Four of 20 cord blood samples had HLA-matched to the affected siblings. One patient underwent cord blood transplantation with success; one patient is waiting for transplantation.

Reverse dot-blot detection of Thai beta-thalassaemia mutations

Pending curative therapy, newborn screening and prenatal diagnosis are essential to the management of beta thalassaemia. Diagnosis using electrophoretic methods is difficult in the presence of composite phenotypes and high Hb F levels. Direct DNA detection of mutant alleles circumvents both problems, but the enormous diversity of beta-thalassaemia mutations poses challenges for this approach. Among PCR-based tests, the reverse dot-blot method enables screening several mutations with a single hybridization reaction. Unfortunately it has often been targeted to only the common mutations of a particular ethnic population, necessitating the use of more arduous detection methods for the less common mutations. We developed a reverse dot-blot strip for the 10 beta-thalassaemia mutations, including the beta-thalassaemic haemoglobinopathies Hb E and Hb Malay, that account for 96% of beta thalassaemia in Thailand, and another strip for six less common Thai mutations. The second strip precludes the need for more technically challenging methods. To avoid problems associated with secondary structure of amplified full-length target DNA, we amplified and labelled beta-globin DNA as two shorter fragments that encompassed all known Thai mutations. Reverse dot-blotting is a rapid, accurate method for detecting beta-thalassaemia mutations.

Organ-specific crystalline structures of ferritin cores in beta-thalassemia/hemoglobin E

The cores of ferritins isolated from different organs of human subjects with beta-thalassemia/hemoglobin E (beta-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy. beta-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases of beta-thal/HbE subjects were found to have larger, more crystalline cores than those from the beta-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.

Ultrasonographic method for detection of haemoglobin Bart's hydrops fetalis in the second trimester of pregnancy

In nine pregnant women at risk for fetal alpha-thalassaemia, the two affected fetuses were diagnosed by ultrasonography at 18-20 weeks' gestation. In countries with limited resources, ultrasonography provides a cost-effective method of prenatal screening for this condition.

Beta-thalassaemia/haemoglobin E tissue ferritins. II: A comparison of heart and pancreas ferritins with those of liver and spleen

Tissue ferritins from beta-thalassaemia/haemoglobin E heart and pancreas were characterized by native PAGE, SDS/PAGE and isoelectric focussing, and compared with those isolated from corresponding liver and spleen tissue. On PAGE, all ferritins consisted of a single band assigned to the protein monomer. Small differences in electrophoretic mobility were found between the bands. The ferritins were resolved by SDS/PAGE into two major subunits, H and L, corresponding to molecular masses of 22.5 kDa and 19 kDa, respectively. The L subunit was predominant in all cases. The isoferritin profiles of all tissue ferritins were remarkably similar, consisting of a complex pattern of bands which were appreciably more basic than those obtained for horse spleen ferritin. The subunit composition and isoferritin profiles of the four tissue ferritins almost certainly reflect the defense mechanism of the body in synthesizing in all four tissue types a more stable long-term iron-storage isoferritin in order to detoxify and store the excess iron present due to the pathological condition of beta-thalassaemia/HbE.

Beta-thalassaemia/haemoglobin E tissue ferritins. I: Purification and partial characterization of liver and spleen ferritins

Ferritins from liver and spleen of both beta-thalassaemia/haemoglobin E (HbE) and non-thalassaemic patients were purified by heating a methanol-treated homogenate, followed by molecular exclusion chromatography. The concentrations of ferritins in the beta-thalassaemia/HbE liver and spleen were calculated as 3.8 and 2.0 mg/g wet tissue. The beta-thalassaemia/HbE ferritin iron/protein ratios were higher than those of normal ferritins. On PAGE, all ferritins gave a single major monomeric band with only very small differences in their mobility. Ferritins from thalassaemic patients also possessed bands corresponding to oligomers. On SDS/PAGE, all ferritins were resolved into two major subunits: H and L with L subunit predominating. While the isoferritin profiles of ferritins from beta-thalassaemia/HbE liver and spleen were similar to each other and to those of normal liver and spleen, some extra bands were present in the acidic region. The microstructure of these pathological ferritins appears to result, to a large degree, from the particular nature and amount of iron loading present.

Spinal space occupying lesions in thalassemia major

A 17 year old patient suffering from thalassemia, who had been dependent on transfusions since the age of three, showed an increasing incomplete sensory and motor transverse cord lesion below T-10. The causes were found to be multiple epidural erythropoietic foci, confirmed by myelography, CT, and biopsy. The lesions were located in the thoracic, lumbar, and sacral regions. Complete remission of the neurological symptoms was achieved by an immediate hypertransfusion regimen and subsequent local radiation therapy of the neuroaxis. Thirty-six cases of thalassemia and spinal space occupying lesions have been reported in the literature. The therapeutic results of these are presented and compared with our findings.

Thalassemia in the Silk Road region of China

This paper summarizes data obtained during a screening program involving 11,563 persons from the Silk Road region in China. The mean incidence of thalassemia is 1.62% with an increase from east to west. The incidence in the Hui population (3.01%) is higher than in Kazaks (2.92%), and in Uygur (2.22%). The Han population also has a higher incidence (0.98%) than seen for other regions in Northern China. The thalassemias observed are classified into seven groups; beta-thalassemia accounts for 89.48% of the total, and alpha-thalassemia for 10.52%.

Identification of Hb Lepore-Washington-Boston in association with Hb E [beta 26(B8)Glu----Lys] in a Thai female

The proposita was a Thai female showing signs of a mild anemia (Hb: 11.4 g/dl; RBC: 4.91 X 10(6)/mm3; reticulocytes: 2.4%; MCV: 70 fl; MCHC: 23.3 g/dl). Hemoglobins were isolated by DEAE-cellulose chromatography in the following relative amounts: Hb E + Hb A2 = 53%; Hb F0 = 30.0%; Hb delta beta-Lepore = 12.7%; Hb F1 = 4.3%. The beta E and delta beta-Lepore chains were isolated by CM-cellulose chromatography and were subjected to tryptic peptide mapping on paper in comparison to normal beta A chains. Amino acid analysis of selected peptides permitted unambiguous identification of the abnormal hemoglobins as Hb E [beta 26(B8)Glu----Lys] and Hb Lepore-Washington-Boston, which has a delta chain sequence for residues 1-87, and a beta chain sequence for residues 116-146. The presence of a Lepore hemoglobin was further confirmed by Pst I digestion of the proposita's DNA. The association of the two hemoglobin variants gave rise to elevated levels of Hb F.

Hereditary red cell disorders in Southeast Asian refugees and the effect on the prevalence of thalassemia disorders in the United States

This investigation established the frequency and prevalence of hemoglobin E, alpha and beta thalassemia, and glucose-6-phosphate dehydrogenase deficiency in a group of Southeast Asian individuals and determined the impact upon the prevalence of thalassemia disorders in the United States. The resettlement program of Southeast Asian refugees has significantly increased the total number of serious thalassemic disorders in the United States. For several generations Southeast Asian children will be the principal thalassemic group.

Hematologic genetic disorders among Southeast Asian refugees

Resettlement of Southeast Asian refugees has introduced into the Western Hemisphere many persons of all major ethnic groups from Indochina. They represent several distinctive cultural, genetic, and linguistic groups, and the prevalence of genetic traits among them varies accordingly. We studied 778 Southeast Asian persons resettled in the upper Midwest who belonged to 182 unrelated families from the five major Southeast Asian ethnic groups. High prevalences of hemoglobin E, alpha- and beta-thalassemia disorders, and glucose-6-phosphate dehydrogenase deficiency were found. The prevalences of these four conditions in the refugees are among the highest known in the world. For these groups, iron deficiency is an uncommon cause of microcytosis; instead, the most frequent causes are hemoglobin E and alpha-thalassemia-1. Very serious thalassemic disorders occur with unusually high frequency in the refugees, especially in the Tai-Dam.

A screening protocol for a prenatal population at risk for inherited hemoglobin disorders: results of its application to a group of Southeast Asians and blacks

Several inherited hemoglobin disorders are present among certain racial subgroups of the United States population, particularly among blacks and Southeast Asians. Many of these disorders are unfamiliar to the obstetrician-gynecologist but may have important implications for care in pregnancy, including genetic counseling and prenatal diagnosis. A simple, effective screening tool was devised for detection of thalassemias and hemoglobinopathies in a prenatal clinic population. Use of the tool resulted in diagnosis of a hemoglobin disorder in 20% of a group of black patients; diagnoses included alpha-thalassemia trait, beta-thalassemia trait, hemoglobin C trait, hemoglobin S/C disease, hemoglobin S trait, sickle cell anemia, and hemoglobin Lepore. In a group of Southeast Asian patients, 39% had a hemoglobin disorder, including alpha-thalassemia trait, beta-thalassemia trait, hemoglobin E disease, and hemoglobin H disease. Implications for care are discussed.

Ultrastructure and cell cycle distribution of erythropoietic cells in heterozygotes and homozygotes for haemoglobin E

Marrow aspirates from heterozygotes and homozygotes for haemoglobin E (HbE) have been studied by electron microscopy and by the technique of combined Feulgen microspectrophotometry and 3H-thymidine autoradiography. The erythropoietic cells of heterozygotes did not contain any precipitated globin chains and the proliferating erythroblasts of such individuals showed no abnormality in their distribution in the different stages of interphase. By contrast, 0-1.5% of late erythroblast profiles and 3.1-12.8% of marrow reticulocyte profiles of homozygotes contained intracellular inclusions resembling precipitated alpha-chains. Although precipitated globin chains were not seen in the early polychromatic erythroblasts of homozygotes, the number of these cells in the G2 phase relative to that in the S phase was increased. These data indicate that there is probably little or no imbalance of globin chain synthesis in heterozygotes, a substantial degree of imbalance in homozygotes, and a disturbance of erythroblast proliferation in homozygotes which cannot be attributed to the deleterious effects of detectable intracellular alpha-chain precipitates. The electron microscope and cell cycle distribution data in the homozygotes for HbE were similar to those in two heterozygotes for beta thalassaemia.

Non-transferrin plasma iron in beta-thalassaemia/Hb E and haemoglobin H diseases

Non-transferrin plasma iron concentrations were determined in 45 normal controls and in 37 patients with Hb H disease and 104 patients with beta-thalassaemia/Hb E disease. This revealed that non-transferrin plasma iron exists in cases with severe iron overload, more striking in beta-thalassaemia/Hb E than in Hb H disease. Non-transferrin plasma iron is associated with higher transferrin iron saturation and higher plasma ferritin levels. The most striking finding was the significantly higher non-transferrin plasma iron in splenectomized patients with beta-thalassaemia/Hb E disease than in the non-splenectomized patients. In view of the potential toxicity of non-transferrin iron, this fraction of iron may be responsible for tissue damage in these patients especially after splenectomy.

Ineffective erythropoiesis in haemoglobin E beta -thalassaemia: an electron microscope study

Electron microscope studies have been performed on the bone marrow cells of two non-splenectomized patients and the circulating erythroblasts and reticulocytes of three splenectomized patients with HbE/beta-thalassaemia. Some intracellular precipitates (probably consisting of alpha-chains) and mild dyserythropoietic changes were found in the early polychromatic erythroblasts within the bone marrow. Larger quantities of precipitate and more marked dyserythropoietic changes were found in the late polychromatic erythroblasts and reticulocytes both within the marrow and within the circulation. The bone marrow macrophages contained phagocytosed erythroblasts within their cytoplasm. These data indicate that the anaemia in HbE/beta-thalassaemia results largely from dyserythropoiesis and ineffective erythropoiesis. The ultrastructural abnormalities encountered in the cases of HbE/beta-thalassaemia were qualitatively and quantitatively similar to those seen in homozygous beta-thalassaemia.