Markissia Karagiorga

Phenotypic and molecular diversity of haemoglobin H disease: a Greek experience

Haemoglobin H (Hb H) disease is the severest form of α‐thalassaemia compatible with post‐natal life and occurs when α‐thalassaemia mutations interact to reduce α‐globin synthesis to levels approximately equivalent to the output of a single α‐globin gene. Hb H disease has variable clinical expression, mainly related to underlying genotypes. The spectrum of α‐thalassaemia determinants in Greece appears greater than in any other population studied and, in 75 Greek Hb H disease patients, we found 12 α‐thalassaemia mutations interacting to produce 15 Hb H disease genotypes. Evaluation of haematological, biochemical and clinical findings, and correlation with genotypes, defined genetic predictors of disease severity and factors involved in disease progression. In accordance with previous reports, patients with non‐deletion α‐thalassaemia mutations had more severe clinical expression. Additionally, we found that all patients with the most severe phenotypes had α‐thalassaemic globin variants. Phenotypic severity was not simply related to the degree of α‐globin deficiency: high Hb H levels were found to exacerbate anaemia by negatively influencing tissue oxygenation, and both Hb H and α‐thalassaemic haemoglobin variants appear to reduce red cell survival within the bone marrow and circulation. Together with the long‐term follow‐up in many patients, this report provides comprehensive information for management of Hb H disease and appropriate family counselling.

Dose of desferrioxamine and evolution of HIV-1 infection in thalassaemic patients.

To study the relationship between the dose of desferrioxamine (DFX) and the progression of the HIV‐1 disease in thalassaemia major patients (TMP), 64 seropositive TMP patients were studied. Cumulative incidence of CDC stage IV was calculated using a non‐parametric life‐table method. The association with the mean daily dose of DFX was tested with a Cox proportional hazards model which was also used to adjust for confounding variables. The median of the mean daily dose of DFX over the seropositive period was 40mg/kg (range 0‐65mg/kg). Age at seroconversion (P < 0.02) and splenectomy (P < 0.03) were found to be associated with the mean daily dose of DFX. 6.5 years after seroconversion, 11% of those who had been prescribed more than 40mg/kg of DFX daily had entered stage IV versus 35% of those who had been prescribed a lower dose (P < 0.01). When the dose was taken as a continuous variable it was found that the rate of progression was significantly smaller in TMP receiving a higher dose (P < 0.002). even after adjusting for age and splenectomy (P < 0.02). Although it should be noted that these results were obtained in an observational study, possibly biased by a non‐random allocation of the DFX dose, we believe that they are striking enough to support the claim that the role of DFX in the progression of HIV disease should be further evaluated.

Effect of deferiprone or deferoxamine on right ventricular function in thalassemia major patients with myocardial iron overload

BackgroundThalassaemia major (TM) patients need regular blood transfusions that lead to accumulation of iron and death from heart failure. Deferiprone has been reported to be superior to deferoxamine for the removal of cardiac iron and improvement in left ventricular (LV) function but little is known of their relative effects on the right ventricle (RV), which is being increasingly recognised as an important prognostic factor in cardiomyopathy. Therefore data from a prospective randomised controlled trial (RCT) comparing these chelators was retrospectively analysed to assess the RV responses to these drugs.MethodsIn the RCT, 61 TM patients were randomised to receive either deferiprone or deferoxamine monotherapy, and CMR scans for T2* and cardiac function were obtained. Data were re-analysed for RV volumes and function at baseline, and after 6 and 12 months of treatment.ResultsFrom baseline to 12 months, deferiprone reduced RV end systolic volume (ESV) from 37.7 to 34.2 mL (p = 0.008), whilst RV ejection fraction (EF) increased from 69.6 to 72.2% (p = 0.001). This was associated with a 27% increase in T2* (p < 0.001) and 3.1% increase in LVEF (p < 0.001). By contrast, deferoxamine showed no change in RVESV (38.1 to 39.1 mL, p = 0.38), or RVEF (70.0 to 69.9%, p = 0.93) whereas the T2* increased by 13% (p < 0.001), but with no change in LVEF (0.32%; p = 0.66). Analysis of between drugs treatment effects, showed significant improvements favouring deferiprone with a mean effect on RVESV of -1.82 mL (p = 0.014) and 1.16% for RVEF (p = 0.009). Using regression analysis the improvement in RVEF at 12 months was shown to be greater in patients with lower baseline EF values (p < 0.001), with a significant difference in RVEF of 3.5% favouring deferiprone over deferoxamine (p = 0.012).ConclusionIn this retrospective analysis of a prospective RCT, deferiprone monotherapy was superior to deferoxamine for improvement in RVEF and end-systolic volume. This improvement in the RV volumes and function may contribute to the improved cardiac outcomes seen with deferiprone.

Rapid and accurate quantitation of Hb Bart's and Hb H using weak cation exchange high performance liquid chromatography: correlation with the alpha-thalassemia genotype.

The Bio-Rad Variant Hemoglobin testing system is an automated high performance liquid chromatography analyzer marketed with a beta-thalassemia short program to quantify Hbs F and A2, and assist in detecting Hbs A, S, D, C, and E. Although the two hemoglobins present in Hb H disease, Hb Barts and Hb H, are separated by the system, they are not quantitated. In this study we modified the beta-thalassemia short program in order to facilitate quantitation of Hb Barts and Hb H. Blood samples from 60 patients with Hb H disease, with various underlying genotypes, were studied. Analyses were performed on the day of blood collection or on hemolysates stored at -80 degrees C in cyanide or carbomonoxy forms. The mean sum of Hb Barts and Hb H levels in all patients was found to be 12% (range 1.8-35%). Patients with nondeletional mutations (or association of alpha(0) deletion and nondeletional mutations) had notably higher Hb Barts and Hb H levels when compared to patients with deletional genotypes.

Erythroid marrow activity and hemoglobin H levels in hemoglobin H disease

Purpose: To determine serum immunoreactive erythropoietin (Epo) and soluble transferrin receptors (sTfR) levels in patients with hemoglobin H (HbH) disease and the correlation with HbH levels and α-globin genotype. Patients and Methods: Twenty patients with HbH disease were studied. Methods applied included cation-exchange high pressure liquid chromatography for HbH levels, chemoluminescence for Epo concentration, immunoassay for sTfR concentration, and DNA analysis for a-globin genotype characterization. Results: Serum Epo and sTfR levels were significantly elevated (46.6 + 26.8 IU/1 and 5.6 + 1.8 mg/1, respectively) in patients with HbH disease compared to controls (9.2 + 3.3 IU/1 and 1.8 + 0.7 mg/1. respectively). Epo and sTfR levels correlated positively with HbH concentration (r = 0.93 and 0.80, respectively). The highest Epo and sTfR values were observed in three patients with the highest HbH levels who all had nondeletion α-thalassemia mutations. Conclusion: Epo and sTfR levels are increased in patients with HbH disease; this increase is directly related to the HbH concentration that usually reflects the degree of globin polypeptide imbalance. The correlation of Epo. sTfR, and reticulocyte production index in these patients indicates that anemia in HbH disease mainly is caused by ineffective erythropoiesis and a mild degree of peripheral hemolysis.

Interaction of an α+-Thalassemia Deletion with Either a Highly Unstable α-Globin Variant (α2, Codon 59, GGC→GAC) or a Nondeletional α-Thalassemia Mutation (AATAA→AATAAG): Comparison of Phenotypes Illustrating “Dominant” α-Thalassemia

Thalassemia syndromes and unstable hemoglobins traditionally represent two phenotypically separate disorders of hemoglobin synthesis. Highly unstable hemoglobin variants, however, often have phenotypic characteristics associated with both ineffective erythropoiesis (thalassemias) and peripheral hemolysis (unstable hemoglobins). Many highly unstable β chain variants cause a dominant thalassemia-like phenotype, in which simple heterozygotes for such mutations have a clinical expression similar to thalassemia intermedia. The phenotypic expression of highly unstable α-globin variants is usually less severe, due mainly to a gene dosage effect, and they are often only characterized on interaction with other α-thalassemia mutations, whence they are classified as nondeletional α-thalassemia determinants. This study reports the clinical and hematological findings in five cases with rare α-thalassemia genotypes: a single patient with the thalassemic α2-globin gene codon 59 Gly→Asp hemoglobin variant in trans to an ...

Correlation of echocardiography parameters with cardiac magnetic resonance imaging in transfusion-dependent thalassaemia major.

Background and objective: Heart iron load (cardiac Fe) can be indirectly quantified by cardiac magnetic resonance (CMR) T2*. CMR accessibility is limited, whereas echocardiography (Echo) is relatively inexpensive and readily available. The objective was to find Echo parameters that may be useful for predicting cardiac Fe. Design and methods: We compared a number of parameters derived from Echo to cardiac Fe in 142 thalassaemia major patients who had undergone a CMR study. Results: All patients with decreased left ventricular (LV) function had cardiac Fe. After removing those patients from the analysis, the total diameter index (Tdi) >5.57 cms/m2, left atrial diameter index >2.41 cm/m2, and the diastolic parameter E/A > 1.96 were highly specific (91.4%, 97.1% and 96.9% respectively) but had low sensitivity (31.8%, 20.45% and 21.8%) in predicting iron load. A right ventricular index >1.47 cm/m2, LV systolic index >2.26 cm/m2 or Tdi >6.26 cm/m2 discriminated between patients with no, or mild to moderate cardiac Fe from those with heavy load, with specificity of 91%, 98.5%, and 98.5%, respectively, but with low sensitivity. Interpretation and conclusions: Echo parameters for cardiac Fe prediction have restricted value, whereas CMR is essential to assess cardiac Fe. However, patients with decreased LV systolic function should be considered a priori as having cardiac Fe, and chelation therapy should be intensified. This also applies to patients who have the above‐described Echo criterion values, even if CMR is not available. Once a patient is found by CMR to have cardiac Fe, then the above Echo criterion values may be useful for ongoing monitoring.

Liver disease in adult transfusion‐dependent beta‐thalassaemic patients: investigating the role of iron overload and chronic HCV infection

Iron overload and hepatitis‐C virus (HCV) infection, have been implicated in the evolution of liver disease, in patients with transfusion‐dependent beta‐thalassaemia major (BTM). However, the impact of these factors in late stages of liver disease in adults with BTM, has not been extensively studied.

Iron Overload, Cardiac and Other Factors Affecting Pregnancy in Thalassemia Major

The reproductive thalassemic population is growing older and doctors confront the challenge of the thalassemic pregnancy. Pregnancy is characterized by dynamic multiple system changes, resulting in increased basal oxygen consumption, changes in energy substrate use by different organs and increased susceptibility to oxidative stress, while homozygous transfusion-dependent β-thalassemia (β-thal) patients manifest cardiac, hepatic, endocrine, and metabolic disorders attributable to chronic anoxia and iron overload. Pregnant thalassemic patients require significantly larger amount of total blood transfusion during pregnancy and iron overload increases the oxidative stress of pregnancy, while the risk for cardiovascular events, in a high cardiac output state, is augmented and chelation treatment is generally avoided due to the potential teratogenicity. Pregnancy in thalassemia major should be considered high risk, and be cared for by an expert team with special caution and sensitivity.

Unusual phenotypic observations associated with a rare HbH disease genotype (- -Med/αTSaudiα): implications for clinical management

Summary.  A single patient with a rare Haemoglobin H (HbH) disease genotype (‐ ‐Med/αTSaudiα) was observed to have exceptionally high levels of HbH (> 60%) and paradoxically high total haemoglobin levels. Studies of haematological parameters, blood biochemistry and oxygen transport properties revealed a severe functional anaemia, associated with marked erythropoietic stimulation and a markedly raised cardiac output. This rare case illustrates the complexity of interactions that may be associated with the clinical course of HbH disease, highlighting that haematological parameters alone may lead to spurious evaluation of clinical status. Issues related to the therapeutic management of unusual cases are raised.