Browsing by Author "Weatherall, D.J."

Now showing 1 - 20 of 37

Age-related changes in adaptation to severe anemia in childhood in developing countries
(National Academy of Sciences, 2007) O Donnell, A.; Premawardhena, A.; Arambepola, M.; Allen, S.J.; Peto, T.E.; Fisher, C.A.; Rees, D.C.; Olivieri, N.F.; Weatherall, D.J.
Severe forms of anemia in children in the developing countries may be characterized by different clinical manifestations at particular stages of development. Whether this reflects developmental changes in adaptation to anemia or other mechanisms is not clear. The pattern of adaptation to anemia has been assessed in 110 individuals with hemoglobin (Hb) E beta-thalassemia, one of the commonest forms of inherited anemia in Asia. It has been found that age and Hb levels are independent variables with respect to erythropoietin response and that there is a decline in the latter at a similar degree of anemia during development. To determine whether this finding is applicable to anemia due to other causes, a similar study has been carried out on 279 children with severe anemia due to Plasmodium falciparum malaria; the results were similar to those in the patients with thalassemia. These observations may have important implications both for the better understanding of the pathophysiology of profound anemia in early life and for its more logical and cost-effective management.
Cardiac functions in older patients with haemoglobin E- β thalassaemia
(Sri Lanka Medical Association, 2007) Premawardhena, A.P.; Wanninayake, S.; Dolapihilla, S.N.; Kapuruge, L.; Katugaha, N.; Olivieri, N.F.; Weatherall, D.J.
INTRODUCTION: Cardiac disease accounts for most deaths in patients with thalassaemia. Little is known about cardiac functions in ageing patients with thalassaemia OBJECTIVE: To study cardiac functions in older patients with haemoglobin E - p thalassaemia. DESIGN, SETTING AND METHODS: All patients with haemoglobin E - p thaiassaemia over the age of 24 attending the Thalassaemia Centre at Kurunegala were studied. Data were collected on biographs, transfusion load, body iron loads, ischaemic heart disease risk factors and symptoms and signs of heart disease. Serum lipids, 2D-echo and exercise ECG in addition to basic biochemical investigations were assessed in all. Those with a positive exercise ECG underwent stress echocardiography. Data from age-sex matched "healthy" individuals from the same geographic area were used for comparison. RESULTS: Total of 26 patients and 26 controls were studied. The median age was 34.25 years (24-50). Fourteen females were present in either group. 24% of controls, but-none in thalassaemic families had a family history of ischaemic heart disease. Twelve patients with thalassaemia and one control had a positive exercise ECG. All 12 with positive exercise ECG had normal stress echocardiography. Severe hypocholesterolaemia (mean total cholesterol 90.5 vs 376.9mg/dl) was present in all patients with thalassaemia. Pulmonary hypertension was noted in 7 patients with thalassaemia (not in controls). Nine patients with thalassaemia but none of the controls showed diastolic dysfunction. CONCLUSION: The study shows unique cardiac abnormalities that occur in patients with haemoglobin E- β thalassaemia. The marked hypocholesterolaemia may reduce the risk of ischaemic heart disease but significant right heart damage seems to occur in these chronically anaemic patients.
Chracterisation of beta giobin mutations in Sri Lankan patients with betathalassaemia intermedia
(Sri Lanka Medical Association, 2013) Perera, S.; Silva, D.P.S.I.; Hapugoda, M.; Wickramarathne, M.N.; Wijesirwardhena, I.; Efremove, D.G.; Fisher, C.A.; Weatherall, D.J.; Premawardhena, A.P.
INTRODUCTION AND OBJECTIVES: Patients with beta thalassaemia intermedia account for a third of patients attending thalassaemia clinics in Sri Lanka. They show immense phenotypic diversity, the genetic basis for which has not been identified so far. Objective were to characterise beta globin gene mutations in Sri Lankan thalassaemia intermedia patients and to determine how it to influences disease severity. METHODS: We identified 64 thalassaemia intermedia patients from the five main thalassaemia centers; Anuradhapura (n= 6), Kuruncgala (n= 4), Ragama (n= 42), Badulla (n=7) and Chilaw (n=5). Their beta globin DNA sequences were analyzed using ABI PRISM 313lx genetic analyser. RESULTS: Of sixteen patients identified to be homozygous for beta mutations, eleven carried mild beta alleles, IVSI 5 G_C (n= 10) and a rare homozygous promoter mutation - 90 C_T (N=l). Other five were shown to have different types of severe iputations in homozygous state. Nearly half the sample (n=39) was heterozygous for beta mutations. Of them 33 showed mild to severe mutation in one of the alleles IVSI-5 G_C (n=12), IVSI-1 G_A (n= 11) were the commonest. Two patients who were hetcrozygones for beta mutation had a highly unstable Hb variant haemoglobin Mizuho causing severe haemolytic anacma. Hb variants Hb G-Szuhu and Hb G-Coushatta were identified in two patients. CONCLUSIONS: We identified types of beta mutations in some patients with thalassaemia intermedia, which account for the clinical severity.
Clinical and molecular heterogeneity among Beta Thalassaemia Intermedia in Sri Lanka
(Sri lanka Medical Association, 2015) Perera, P.S.; Silva, D.P.S.I.; Hapugoda, M.; Wickramarathne, M.N.; Wijesiriwardena, I.; Efremov, D.G.; Fisher, C.A.; Weatherall, D.J.; Premawardhena, A.
INTRODUCTION AND OBJECTIVES: Patients with beta thalassaemia intermedia (Tl) unrelated to haemoglobin E/beta thalassaemia account for an important minority in thalassaemia clinics in Sri Lanka. We investigated the genotypic/phenotypic diversity of this small group of patients. METHOD: Fifty Tl patients identified from five thalassaemia centers were clinically assessed and divided in to severity groups based on agreed criteria. Genetic analysis was done by PCR based techniques. RESULTS: There were 26 mild, 12 moderate and 12 in the severe groups. Ages ranged from 5-65 years. Mean haemoglobin of the whole group was 7.8g/dl. Age at presentation ranged from 3 months - 57 years (mean 16.8yrs) and varied according to severity; 17.8 years in mild to 4.8 years in severe group. 86% were on intermittent transfusions whilst 14% were never transfused. Mean total transfusion load in the three groups ranged from 6, 28 to 89. Majority (60%) had splenomegaly and 12% were splenectomised. The median spleen size of each severity group was 0, 4.5 and 7.5 cm respectively. Thalassaemicfacial features were not_ demonstrable in the majority (86%). Genetic analysis identified the commonest mechanism for Tl to be coexistence of a single beta mutation with excess alpha genes (56%). None of these patients had severe phenotype. Coexistence of two beta mutations with alpha thalassaemia invariably gave rise to severe phenotype. Other mechanisms gave rise to varying disease severity. CONCLUSION: This study highlights the remarkable phenotypic variations in beta Tl in Sri Lanka and identifies some genetic mechanisms which can explain this variation.
The clinical effects of excessive a globin genes : two family studies
(Sri Lanka Medical Association, 2003) Premawardhena, A.P.; Fisher, C.A.; Rugless, M.; de Silva, S.; Perera, A.W.V.S.; Olivien, N.F.; Weatherall, D.J.
INTRODUCTION: Globin chain imbalance is the central pathogenic abnormality in the thalassaemias, a condition where globin gene expression is reduced. Conversely, the inheritance of excess globin genes too may affect the phenotype. However such examples are rarely found. OBJECTIVES: To describe two families in whom the co-existence of excess a genes was noted together with p - thalassaemia trait. METHODS: During the routine P - globin gene analysis in patients attending the Thalassaemia Unit of the Kurunegala Hospital, two patients were identified to have thalassaemia intermedia phenotype, but with just one (3 - thalassaemia mutation. The clinical details of these patients and their families were studied in detail as was their h'aematological and genetic data. RESULTS: We describe two families in which the propositus had inherited six and eight a - genes respectively together with a single p - thalassaemia mutation. Both patients had the thalassaemia intermedia phenotype. The family members who did not inherit any thalassaemic mutations too had varying, but often marked hypochromic microcytosis. DISCUSSION: We describe the first ever family study of a patient with the combination of 8 a - genes and p - thalassaemia trait. We also describe another family where a member had 6 a - genes together with p thalassaemia trait. This highlights yet another mechanism for the intermedia phenotype in patients with a solitary (3 - globin gene mutation. It also highlights the need for the study of a globin genes in patients with unexplained hypochromic microcytic anaemia.
Correlation of genotype with phenotype in beta thalassaemia intermedia in Sri lanka
(Thalassaemia International Federation, 2015) Perera, P.S.; Silva, D.P.S.I.; Hapugoda, M.; Wickramarathne, M.N.; Wijesiriwardena, I.; Efremov, D.G.; Fisher, C.A.; Weatherall, D.J.; Premawardhena, A.
Abstract Available
A Functional element necessary for fetal hemoglobin silencing
(Massachusetts Medical Society, 2011) Sankaran, V.G.; Xu, J.; Byron, R.; Greisman, H.A.; Fisher, C.; Weatherall, D.J.; Sabath, D.E.; Groudine, M.; Orkin, S.H.; Premawardhena, A.; Bender, M.A.
BACKGROUND: An improved understanding of the regulation of the fetal hemoglobin genes holds promise for the development of targeted therapeutic approaches for fetal hemoglobin induction in the β-hemoglobinopathies. Although recent studies have uncovered trans-acting factors necessary for this regulation, limited insight has been gained into the cis-regulatory elements involved. METHODS: We identified three families with unusual patterns of hemoglobin expression, suggestive of deletions in the locus of the β-globin gene (β-globin locus). We performed array comparative genomic hybridization to map these deletions and confirmed breakpoints by means of polymerase-chain-reaction assays and DNA sequencing. We compared these deletions, along with previously mapped deletions, and studied the trans-acting factors binding to these sites in the β-globin locus by using chromatin immunoprecipitation. RESULTS: We found a new (δβ)(0)-thalassemia deletion and a rare hereditary persistence of fetal hemoglobin deletion with identical downstream breakpoints. Comparison of the two deletions resulted in the identification of a small intergenic region required for γ-globin (fetal hemoglobin) gene silencing. We mapped a Kurdish β(0)-thalassemia deletion, which retains the required intergenic region, deletes other surrounding sequences, and maintains fetal hemoglobin silencing. By comparing these deletions and other previously mapped deletions, we elucidated a 3.5-kb intergenic region near the 5' end of the δ-globin gene that is necessary for γ-globin silencing. We found that a critical fetal hemoglobin silencing factor, BCL11A, and its partners bind within this region in the chromatin of adult erythroid cells. CONCLUSIONS: By studying three families with unusual deletions in the β-globin locus, we identified an intergenic region near the δ-globin gene that is necessary for fetal hemoglobin silencing. (Funded by the National Institutes of Health and others.).
Genetic determinants of jaundice and gallstones in haemoglobin E beta thalassaemia
(2001) Premawardhena, A.P.; Fisher, C.A.; Fathihu, F.; de Silva, S.; Perera, W.; Peto, T.E.; Olivieri, N.F.; Weatherall, D.J.
Chronic hyperbilirubinaemia, gallstone formation, and gall bladder disease are unusually common in people with haemoglobin E beta thalassaemia in Sri Lanka. To determine whether this has a genetic basis we compared the bilirubin levels and frequency of gallstones in patients with different alleles of the UGT*1 gene. There was a significantly higher bilirubin level in those with the 7/7 genotypes compared with 6/6 and 6/7 genotype (p=0.032 and 0.0015 respectively), who also appeared more prone to gallstone formation. These results suggest that the UGT*1 genotpe is of importance in the genesis of gallstones in this population of patients.
Genotype-phenotype association analysis identifies the role of α globin genes in modulating disease severity of β thalassaemia intermedia in Sri Lanka
(Nature Publishing Group, 2019) Perera, S.; Allen, A.; Silva, I.; Hapugoda, M.; Wickramarathne, M.N.; Wijesiriwardena, I.; Allen, S.; Rees, D.; Efremov, D.G.; Fisher, C.A.; Weatherall, D.J.; Premawardhena, A.
β thalassaemia intermedia (βTI) are a heterogeneous group of disorders known to be extremely phenotypically diverse. This group is more complex to manage as no definitive treatment guidelines exist unlike for β thalassaemia major (βTM). There are only a few studies looking at genotype phenotype associations of βTI outside the Mediterranean region. The reasons for the diverse clinical phenotype in βTI are unknown. We categorized fifty Sri Lankan patients diagnosed with βTI as mild, moderate or severe according to published criteria. DNA samples were genotyped for β thalassaemia mutations, α globin genotype and copy number and known genetic modifiers of haemoglobin F production. There were 26/50 (52.0%) in mild group and 12/50 (24.0%) each in moderate and sever categories. 18/26 (69.2%) classified as mild were β heterozygotes and 17/18 (94.4%) had excess α globin genes. 11/12 (91.6%) classified as moderate were β heterozygotes and 8/11 (72.2%) had excess α globin genes. In contrast, 8/12 (66.7%) classified as severe were β homozygotes and 7/8(87.5%) had α globin gene deletions. In Sri Lanka, co-inheritance of either excess α globin genes in β thalassaemia heterozygotes or α globin gene deletions in β thalassaemia homozygotes is a significant factor in modulating disease severity
The Global distribution of length polymorphisms of the promoters of the gucuronosyltransferase I gene(UGTIAI): hematologic and evolutionary implications
(Academic Press, 2003) Premawardhena, A.P.; Fisher, C.A.; Liu, Y.T.; Verma, I.C.; de Silva, S.; Arambepola, M.; Clegg, J.B.; Weatherall, D.J.
The promoter region of the UDP glucuronosyltransferase 1 gene (UGT1A1) contains a run of thymine-adenine (TA) repeats, usually six (TA)(6). As well as its relationship to Gilbert's syndrome, homozygosity for the extended sequence, (TA)(7) (TA)(7), has been found to be an important risk factor for hyperbilirubinemia and gallstones in patients with hemoglobin E-beta-thalassemia and other intermediate forms of beta thalassemia. To assess the importance of this polymorphism in these common disorders a wide-scale population study of the relative frequency of the size alleles of the UGT1A1 promoter has been carried out. Homozygosity for the (TA)(7) allele occurs in 10-25% of the populations of Africa and the Indian subcontinent, with a variable frequency in Europe. It occurs at a much lower frequency in Southeast Asia, Melanesia, and the Pacific Islands, ranging from 0 to 5%. African populations show a much greater diversity of length alleles than other populations. These findings define those populations with a high frequency of hemoglobin E-beta-thalassemia and related disorders that are at increased risk for hyperbilirubinemia and gall bladder disease and provide evolutionary insights into how these polymorphisms have arisen and are so unequally distributed among human populations.
Haemoglobin E beta thalassaemia in Sri Lanka
(Lancet Publishing Group, 2005) Premawardhena, A.; Fisher, C.A.; Olivieri, N.F.; de Silva, S.; Arambepola, M.; Perera, W.; O Donnell, A.; Peto, T.E.; Viprakasit, V.; Merson, L.; Muraca, G.; Weatherall, D.J.
Haemoglobin E beta thalassaemia is the commonest form of severe thalassaemia in many Asian countries, but little is known about its natural history, the reasons for clinical diversity, or its management. We studied 109 Sri Lankan patients with the disorder over 5 years. 25 patients were not receiving transfusion; transfusion was stopped with no deleterious effect in a further 37. We identified several genetic and environmental factors that might contribute to the phenotypic diversity of the disorder, including modifiers of haemoglobin F production, malaria, and age-related changes in adaptive function. Our findings suggest that haemoglobin E beta thalassaemia can be managed without transfusion in many patients, even with low haemoglobin levels. Age-related changes in the pattern of adaptation to anaemia suggest that different and more cost-effective approaches to management should be explored.
Haemoglobin variants, iron status and anaemia in Sri Lankan adolescents with low red cell indices: A cross sectional survey
(Academic Press, 2018) Rodrigo, R.; Allen, A.; Manamperi, A.; Perera, L.; Fisher, C.A.; Allen, S.; Weatherall, D.J.; Premawardhena, A.
Iron deficiency complicates the use of red cell indices to screen for carriers of haemoglobin variants in many populations. In a cross sectional survey of 7526 secondary school students from 25 districts of Sri Lanka, 1963 (26.0%) students had low red cell indices. Iron deficiency, identified by low serum ferritin, was the major identifiable cause occurring in 550/1806 (30.5%) students. Low red cell indices occurred in iron-replete students with alpha-thalassaemia including those with single alpha-globin gene deletions. Anaemia and low red cell indices were also common in beta-thalassaemia trait. An unexpected finding was that low red cell indices occurred in 713 iron-replete students with a normal haemoglobin genotype. It is common practice to prescribe iron supplements to individuals with low red cell indices. Since low red cell indices were a feature of all forms of α thalassaemia and also of iron deficiency, in areas where both conditions are common, such as Sri Lanka, it is imperative to differentiate between the two, to allow targeted administration of iron supplements and avoid the possible deleterious effects of increased iron availability in iron replete individuals with low red cell indices due to other causes such as α thalassaemia.
Hemoglobin E-beta-thalassemia: Progress report from the international study group
(Blackwell Publishing, 2005) Premawardhena, A.; de Silver, S.; Arambepola, M.; Olivieri, N.F.; Vichinsky, E.P.; Merson, L.; Muraco, G.; Allen, A.; Fisher, C.; Peto, T.; Weatherall, D.J.
A long-term observational study of Hb E-beta-thalassemia in Sri Lanka is beginning to define some of the genetic and environmental factors that are responsible for its remarkable phenotypic variability. In this population there is a very small difference between the steady-state hemoglobin levels between the mild and severe phenotypes, and it has been possible to stop transfusion in many of those who have been on long-term treatment of this kind. These preliminary observations, made over the last 7 years, provide directions for future research into this increasingly important disease.
Hepcidin detects iron deficiency in Sri Lankan adolescents with a high burden of hemoglobinopathy: A diagnostic test accuracy study
(Wiley-Blackwell, 2017) Wray, K.; Allen, A.; Evans, E.; Fisher, C.; Premawardhena, A.; Perera, L.; Rodrigo, R.; Goonathilaka, G.; Ramees, L.; Webster, C.; Armitage, A.E.; Prentice, A.M.; Weatherall, D.J.; Drakesmith, H.; Pasricha, S.R.
Anemia affects over 800 million women and children globally. Measurement of hepcidin as an index of iron status shows promise, but its diagnostic performance where hemoglobinopathies are prevalent is unclear. We evaluated the performance of hepcidin as a diagnostic test of iron deficiency in adolescents across Sri Lanka. We selected 2273 samples from a nationally representative cross-sectional study of 7526 secondary schoolchildren across Sri Lanka and analyzed associations between hepcidin and participant characteristics, iron indices, inflammatory markers and hemoglobinopathy states. We evaluated the diagnostic accuracy of hepcidin as a test for iron deficiency with estimation of the AUCROC , sensitivity/specificity at each hepcidin cutoff, and calculation of the Youden Index to find the optimal threshold. Hepcidin was associated with ferritin, sTfR and hemoglobin. The AUCROC for hepcidin as a test of iron deficiency was 0.78; hepcidin outperformed Hb and sTfR. The Youden index-predicted cutoff to detect iron deficiency (3.2ng/mL) was similar to thresholds previously identified to predict iron utilization and identify deficiency in African populations. Neither age, sex, nor α- or β-thalassemia trait affected diagnostic properties of hepcidin. Hepcidin pre-screening would prevent most iron-replete thalassemia carriers from receiving iron whilst still ensuring most iron deficient children were supplemented. Our data indicate that the physiological relationship between hepcidin and iron status transcends specific populations. Measurement of hepcidin in individuals or populations could establish the need for iron interventions. This article is protected by copyright. All rights reserved.
Hepcidin is suppressed by erythropoiesis in hemoglobin E β-thalassemia and β-thalassemia trait
(American Society of Hematology, 2015) Jones, E.; Pasricha, S.R.; Allen, A.; Evans, P.; Fisher, C.A.; Wray, K.; Premawardhena, A.; Bandara, D.; Perera, A.; Webster, C.; Sturges, P.; Olivieri, N.F.; St Pierre, T.; Armitage, A.E.; Porter, J.B.; Weatherall, D.J.; Drakesmith, H.
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 overallhepcidin inversely correlated with iron accumulation. On segregating by phenotype, there were no differences in hepcidin, erythropoiesis, orhemoglobin 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 oferythropoiesis 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.
Impact of a low transfusion regimen on growth and iron loading in haemoglobin E/beta thalassaemia
(American Society of Hematology, 1999) Olivieri, N.F.; Sharma S.; de Silva, S.; Premawardhena, A.P.; Viens, A.M.; Taylor, C.M.; Symes, K.N.; Vichinsky, E.P.; Brittenham, G.M.; Weatherall, D.J.
Interaction of malaria with a common form of severe thalassemia in an Asian population
(National Academy of Sciences, 2009) O Donnell, A.; Premawardhena, A.; Arambepola, M.; Samaranayake, R.; Allen, S.J.; Peto, T.E.; Fisher, C.A.; Cook, J.; Corran, P.H.; Olivieri, N.F.; Weatherall, D.J.
In many Asian populations, the commonest form of severe thalassemia results from the coinheritance of HbE and beta thalassemia. The management of this disease is particularly difficult because of its extreme clinical diversity; although some genetic and adaptive factors have been identified as phenotypic modifiers, the reasons remain unclear. Because the role of the environment in the course of severe thalassemia has been neglected completely and because malaria due to both Plasmodium falciparum and Plasmodium vivax has been prevalent in Sri Lanka, we carried out a pilot study of patients with HbE beta thalassemia that showed high frequencies of antibodies to both parasite species and that 28.6% of the children had DNA-based evidence of current infection with P. vivax. Malarial antibodies then were assessed in patients with HbE beta thalassemia compared with those in age-matched controls. There was a significant increase in the frequency of antibodies in the thalassemic patients, particularly against P. vivax and in young children. There was also a higher frequency in those who had been splenectomized compared with those with intact spleens, although in the latter it was still higher than that in the controls. The thalassemic patients showed significant correlations between malaria antibody status and phenotype. Patients with HbE beta thalassemia may be more prone to malaria, particularly P. vivax, which is reflected in their clinical severity. Because P. vivax malaria is widespread in Asia, further studies of its interaction with HbE beta thalassemia and related diseases are required urgently as a part of ongoing thalassemia control programs.
Iron overload and iron-chelating therapy in haemoglobin E/beta thalassaemia
(Lippincott Williams and Wilkins, 2000) Olivieri, N.F.; de Silva, S.; Premawardhena, A.P.; Sharma S.; Viens, A.M.; Taylor, C.M.; Brittenham, G.M.; Weatherall, D.J.
Whereas hemoglobin (Hb) E-beta thalassemia is recognized as probably the most common serious hemoglobinopathy worldwide, its natural history remains poorly defined. The interaction of hemoglobin E and beta-thalassemia result in a wide spectrum of clinical disorders, some indistinguishable from thalassemia major and some milder and not transfusion-dependent. Partially as a result of this wide range of phenotypes, clear guidelines for approaches to transfusion and to iron-chelating therapy for patients with Hb E-beta thalassemia have not been developed. By contrast, data that have accumulated during the past 10 years in patients with beta-thalassemia permit a quantitative approach to the management of iron overload and provide guidelines for the control of body iron burden in individual patients treated with iron-chelating therapy. These guidelines may be applicable to patients with Hb E-beta thalassemia. Preliminary evidence from our studies of iron loading in affected patients with Hb E-beta thalassemia in Sri Lanka suggest that this disorder may be associated with variable, but accelerated, gastrointestinal iron absorption, and that the iron loading associated with chronic transfusions in patients with Hb E-beta thalassemia is similar to that observed in patients with beta-thalassemia. These data, in the only cohort of patients with Hb E-beta thalassemia to have undergone quantitative assessment of body iron burden, suggest that the principles that guide assessment of iron loading and initiation of chelating therapy in patients with beta-thalassemia may be generally applicable to those with Hb E-beta thalassemia. Further quantitative studies in both non-transfused and transfused patients will be necessary to permit firm conclusions.
Iron overload in the Asian community
(American Society of Hematology, 2009) Lok, C.Y.; Merryweather-Clarke, A.T.; Viprakasit, V.; Chinthammitr, Y.; Srichairatanakool, S.; Limwongse, C.; Oleesky, D.; Robins, A.J.; Hudson, J.; Wai, P.; Premawardhena, A.; de Silva, H.J.; Dassanayake, A.S.; McKeown, C.; Jackson, M.; Gama, R.; Khan, N.; Newman, W.; Banait, G.; Chilton, A.; Wilson-Morkeh, I.; Weatherall, D.J.; Robson, K.J.H.
Hereditary hemochromatosis is an iron overload disorder that can lead to the impairment of multiple organs and is caused by mutations in one or more different genes. Type 1 hemochromatosis is the most common form of the disease and results from mutations in the HFE gene. Juvenile hemochromatosis (JH) is the most severe form, usually caused by mutations in hemojuvelin (HJV) or hepcidin (HAMP). The autosomal dominant form of the disease, type 4, is due to mutations in the SLC40A1 gene, which encodes for ferroportin (FPN). Hereditary hemochromatosis is commonly found in populations of European origin. By contrast, hemochromatosis in Asia is rare and less well understood and can be masked by the presence of iron deficiency and secondary iron overload from thalassemia. Here, we provide a comprehensive report of hemochromatosis in a group of patients of Asian origin. We have identified novel mutations in HJV, HAMP, and SLC40A1 in countries not normally associated with hereditary hemochromatosis (Pakistan, Bangladesh, Sri Lanka, and Thailand). Our family studies show a high degree of consanguinity, highlighting the increased risk of iron overload in many countries of the developing world and in countries in which there are large immigrant populations from these regions.
Iron status and anaemia in Sri Lankan secondary school children: A cross-sectional survey
(Public Library of Science, 2017) Allen, A.; Allen, S.; Rodrigo, R.; Perera, L.; Shao, W.; Li, C.; Wang, D.; Oliviery, N.; Weatherall, D.J.; Premawardhena, A.P.
BACKGROUND: Iron deficiency, the most common micronutrient disorder and cause of anaemia globally, impairs growth, cognition, behaviour and resistance to infection. METHODS/RESULTS: As part of a national survey of inherited haemoglobin variants in 7526 students from 72 secondary schools purposefully selected from the 25 districts of Sri Lanka, we studied 5912 students with a normal haemoglobin genotype. Median age was 16.0 (IQR 15.0-17.0) years and 3189 (53.9%) students were males. Most students were Sinhalese (65.7%), with fewer Tamils (23.1%) and Muslims (11.2%). Anaemia occurred in 470 students and was more common in females (11.1%) than males (5.6%). Haemoglobin, serum ferritin, transferrin receptor and iron were determined in 1196 students with low red cell indices and a structured sample of those with normal red cell indices (n = 513). The findings were weighted to estimate the frequencies of iron deficiency and iron deficiency anaemia classified according to WHO criteria. Iron depletion (serum ferritin <15ug/ml) occurred in 19.2% and cellular iron deficiency (low serum ferritin and transferrin receptor >28.1 nmol/l) in 11.6% students. Iron deficiency anaemia (cellular iron deficiency with low haemoglobin) occurred in only 130/2794 (4.6%) females and 28/2789 (1.0%) males. Iron biomarkers were normal in 83/470 (14.6%) students with anaemia. In multiple regression analysis, the odds for iron depletion and cellular iron deficiency were about one-third in males compared with females, and the odds for iron deficiency anaemia were about one fifth in males compared to females. Tamil ethnicity and age <16 years increased the risk of all three stages of iron deficiency and living at high altitude significantly reduced the risk of iron depletion. CONCLUSIONS: Low iron status and anaemia remain common problems in Sri Lankan secondary school students especially females, younger students and the socioeconomically disadvantaged Tamil population. More research is needed to identify factors other than low iron status that contribute to anaemia in adolescents.