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During investigations of the phenotypic diversity of hemoglobin (Hb) E β thalassemia, a patient was encountered with persistently high levels of methemoglobin associated with a left-shift in the oxygen dissociation curve, profound ascorbate deficiency, and clinical features of scurvy; these abnormalities were corrected by treatment with vitamin C. Studies of erythropoietin production before and after treatment suggested that, as in an ascorbate-deficient murine model, the human hypoxia induction factor pathway is not totally dependent on ascorbate levels. A follow-up study of 45 patients with HbE β thalassemia showed that methemoglobin levels were significantly increased and that there was also a significant reduction in plasma ascorbate levels. Haptoglobin levels were significantly reduced, and the high frequency of the 2.2 haptoglobin genotype may place an additional pressure on ascorbate as a free-radical scavenger in this population. There was, in addition, a highly significant correlation between methemoglobin levels, splenectomy, and factors that modify the degree of globin-chain imbalance. Because methemoglobin levels are modified by several mechanisms and may play a role in both adaptation to anemia and vascular damage, there is a strong case for its further study in other forms of thalassemia and sickle-cell anemia, particularly when splenic function is defective.

Hemoglobin E (HbE) β-thalassemia is the most common severe thalassemia syndrome across Asia, and millions of people are carriers. Clinical heterogeneity in HbE β-thalassemia is incompletely explained by genotype, and the interaction of phenotypic variation with hepcidin is unknown. The effect of thalassemia carriage on hepcidin is also unknown, but it could be relevant for iron supplementation programs aimed at combating anemia. In 62 of 69 Sri Lankan patients with HbE β-thalassemia with moderate or severe phenotype, hepcidin was suppressed, and overall hepcidin inversely correlated with iron accumulation. On segregating by phenotype, there were no differences in hepcidin, erythropoiesis, or hemoglobin between severe or moderate disease, but multiple linear regression showed that erythropoiesis inversely correlated with hepcidin only in severe phenotypes. In moderate disease, no independent predictors of hepcidin were identifiable; nevertheless, the low hepcidin levels indicate a significant risk for iron overload. In a population survey of Sri Lankan schoolchildren, β-thalassemia (but not HbE) trait was associated with increased erythropoiesis and mildly suppressed hepcidin, suggesting an enhanced propensity to accumulate iron. In summary, the influence of erythropoiesis on hepcidin suppression associates with phenotypic disease variation and pathogenesis in HbE β-thalassemia and indicates that the epidemiology of β-thalassemia trait requires consideration when planning public health iron interventions.

Introduction Worldwide the greatest burden of disease related to beta thalassemia resides in Asia and is largely represented by Hemoglobin E beta thalassemia (HbE/thal) [Weatherall DJ, Ann New York Acad Sci 2005, 1054:11-17]. HbE/thal is the most common serious form of beta thalassemia in many Asian populations. In Sri Lanka, over 17 years, we have characterized over 200 affected patients and had proposed [Olivieri, NF, et al., J Pediatr Hematol Oncol, 2000, 22:593-597], as now shown in less common forms of non-transfusion dependent thalassemia [Taher AT, et al., Br J Haematol 2010, 150:486-489], that non-transfusional iron accumulation (NTIA) is a potential complication in non-transfused patients with HbE/thal. In 2009, we implemented R2-MRI [St Pierre, TG, et al., Blood 2005, 105:855-861] in Sri Lanka. Here we report the variation and severity of non-transfusional iron accumulation (NTIA), in parallel with screening tests of organ dysfunction, in a first group of patients with HbE/thal. Methods Patients aged > 7 years with clinical evidence of iron overload (generally a serum ferritin > normal range in the absence of a history of regular transfusions) were recruited from The National Thalassaemia Centre (NTC), Kurunegala, Sri Lanka. LIC was measured using R2-MRI (FerriScan¨) with facilities situated a 6 hour return bus trip from the NTC. Liver function was evaluated using serum alanine transaminase (ALT). Fasting blood glucose (FBG), thyroid stimulating hormone (TSH), serum calcium and phosphate and serum ferritin (SF) were measured in local laboratories. Cardiac function was measured using echocardiography. Correlations between parameters were assessed using non-parametric (Spearman) analysis. Receiver operating characteristic (ROC) curve analysis was used to determine the optimum cut-off values of LIC and serum ferritin for predicting ALT values above the upper limit of the laboratory reference range. Results LIC measurements were successfully acquired for 110 of 112 enrolled subjects (45 male/ 67 female) with median age [range] 22.5 [7.8 – 61.5] years over 3 years. The variation in LIC was considerably, and unexpectedly, broad: median [range] LIC was 8.8 [0.7 – 65.0] mg Fe/g dw. LIC exceeded the threshold of risk established as 7.0 mg Fe/g dw [Olivieri NF, Brittenham GM, Blood 1997, 89:739-761] in a substantial proportion (57%) of patients. In parallel, organ dysfunction was observed: in a substantial group (52%), ALT was increased above normal range, while in 11%, ejection fraction was reduced (less than 56%). FBG and TSH were elevated above normal range in a substantial proportion of patients (6% and 30% respectively). Significant correlations were observed between LIC and serum ferritin concentration (r2=0.69, p Discussion This study of Asian patients with HbE/thal using R2-MRI, an FDA-approved non-invasive method of evaluation of LIC, reveals a wide range of NTIA and, in parallel, a significant proportion of patients with evidence of liver dysfunction. Our data suggest that the liver is at direct risk from NTIA in HbE/thal at a threshold of 6.35 mg Fe/g dry liver tissue. More robust correlations with dysfunction occurring in other organs may be expected to emerge during longitudinal studies which will be critical to understanding the evolution of organ damage occurring secondary to NTIA in this disorder. These studies are urgently needed to prevent morbidity and premature death in this most common form of beta thalassemia. Disclosures: St Pierre: Resonance Health Ltd: Consultancy, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau. Porter:Novartis: Consultancy, Research Funding; Celgene: Consultancy; Shire: Consultancy.