Iron deficiency anemia and iron overload conditions affect more than one billion people worldwide. Iron homeostasis involves the regulation of cells that export iron into the plasma and cells that utilize or store iron. The cellular iron balance in humans is primarily mediated by the hepcidin-ferroportin axis. Ferroportin is the sole cellular iron export protein, and its expression is regulated transcriptionally, post-transcriptionally and post-translationally. Hepcidin, a hormone produced by liver cells, post-translationally regulates ferroportin expression on iron exporting cells by binding with ferroportin and promoting its internalization by endocytosis and subsequent degradation by lysosomes. Dysregulation of iron homeostasis leading to iron deposition in vital organs is the main cause of death in beta-thalassemia patients. Beta-thalassemia patients show marked hepcidin suppression, ineffective erythropoiesis, anemia and iron overload. Beta-thalassemia is common in the Mediterranean region, Southeast Asia and the Indian subcontinent, and the focus of this review is to provide an update on the factors mediating hepcidin related iron dysregulation in beta-thalassemia disease. Understanding this process may pave the way for new treatments to ameliorate iron overloading and improve the long term prognosis of these patients.
In Southeast Asia, particularly in Thailand, β0-thalassemia/hemoglobin E (HbE) disease is a common hereditary hematological disease. It is associated with pathophysiological processes, such as the intramedullary destruction of immature erythroid cells and peripheral hemolysis of mature red blood cells. MicroRNA (miR) sequences, which are short non-coding RNA that regulate gene expression in a suppressive manner, serve a crucial role in human erythropoiesis. In the present study, the plasma levels of the erythroid-expressed miRNAs, miR-451 and miR-155, were analyzed in 23 patients with β0-thalassemia/HbE and 16 control subjects. Reverse transcription-quantitative polymerase chain reaction analysis revealed significantly higher levels of plasma miR-451 and miR-155 in β0-thalassemia/HbE patients when compared to the control subjects. Notably, among the β0-thalassemia/HbE patients, a significant increase in miR-451 levels was detected in severe cases when compared with mild cases. The levels of plasma miR-451 correlated with reticulocyte and platelet counts. The results suggest that increased plasma miR-451 levels may be associated with the degree of hemolysis and accelerated erythropoiesis in β0-thalassemia/HbE patients. In conclusion, miR-451 may represent a relevant biomarker for pathological erythropoiesis associated with β0-thalassemia/HbE.
Alpha (α)-thalassaemia is one of the most prevalent hereditary blood disorders, commonly affecting Southeast Asian people, with the highest incidence (30–40%) being seen in northern Thailand. However, this high incidence was estimated without consideration of the variations between ethnic populations and the geographical location of the populations. To address this issue, a total of 688 samples from 13 different northern Thai ethnic groups (30 villages) categorized into three linguistic groups were genotyped for deletional alpha-thalassaemia (-α3.7, -α4.2, --SEA and --THAI) and/or non-deletional alpha-thalassaemia (αCS and αPS) via multiplex gap-PCR and dot-blot hybridization, respectively. Alpha+(-α3.7, -α4.2, αCS and αPS) and alpha°-thalassaemia (--SEA and --THAI) allele frequencies (with 95% Confidence Interval) were the highest in the Sino-Tibetan group [0.13 (0.08–0.18)] and the Tai-Kadai group [0.03 (0.02–0.05)], respectively. With regards to ethnicity, the varying allele frequency of α+ and α°-thalassaemia amongst a variety of ethnic groups was observed. The highest α+-thalassaemia allele frequency was found in the Paluang [0.21 (0.10–0.37)] while α°-thalassaemia allele frequency was the highest in the Yuan [0.04 (0.01–0.10)]. These detailed results of alpha thalassaemia allele frequency and genetic diversity amongst the northern Thai ethnic groups demonstrate the need for ethnicity based thalassaemia prevention programs.
Introduction Thalassemias and hemoglobinopathies are the most prevalent inherited anemias detected in South East Asians. These disorders represent not only a clinical health problem but also a socioeconomic problem for this region. Regarding the prevention and control of thalassemias and hemoglobinopathies in the Lao PDR, screening and diagnostic strategies should be strongly considered. The knowledge about the prevalence and molecular genotyping of thalassemias and hemoglobinopathies among the Lao Loum group, which includes the majority of Lao people, is now limited, making the prevention and control of thalassemias difficult. Methods This study aimed to determine the prevalence of thalassemia among Lao Loum subjects of reproductive age. Multiplex gap PCR and direct sequencing were used to investigate the mutations of α‐globin and β‐globin genes. Results Thalassemias and hemoglobinopathies were detected in 154 of 354 (43.50%) patients, and 22 different genotypes were identified in this cohort. Remarkably, high frequencies of hemoglobin E, α0 –thalassemia (‐‐SEA), and α+ –thalassemia (‐α3.7) were noted. A variety of hematologic features was observed, including co‐inheritance of heterozygous HbE and heterozygous α‐thalassemia, which was associated with significantly lower levels of MCV and MCH values than those observed in typical HbE heterozygotes. Female participants who were heterozygous for β0 or co‐inheritance of heterozygous βE with heterozygous α‐thalassemia exhibited mild anemia. Conclusion Our data show that thalassemias and hemoglobinopathies have become health problems imposing a serious burden in the Lao PDR. Prevention programs aimed at decreasing the incidence of severe thalassemia diseases should be designed and initiated.
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common enzyme disorders. Prevalence and variant distribution of G6PD deficiency can vary in different regions and among differing ethnic groups. To reveal the G6PD frequency and molecular characterization among the Lue ethnic group of northern Thailand, blood samples of 296 unrelated individuals collecting from 6 Lue villages were analyzed. The observed G6PD enzyme activity ranged from 0.11 to 20.60 U/g Hb. Overall, 13.51% (40/296) of the individuals were identified as having G6PD deficiency status. The prevalence in males was 14.28% (20/140), while that of females was 12.82% (20/156). The most common G6PD variants in the Lue were the Kaiping 1388G > A (5.40%) and Canton 1376G > T (6.42%) types. Observed prevalence and variant types of the G6PD gene in the Lue population are similar to that of the Tai-Kadai speaking ethnic groups in southern China, which is consistent with their historically close line of ancestry. However, the founder effect that occurred during the Lue’s transboundary migration from China to Thailand showed its impact upon different patterns of G6PD distribution among each Lue village.
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