b-Thalassemia/HbE disease is clinically variable. In searching for genetic factors modifying the disease severity, patients were selected based on their disease severities, and a genome-wide association study (GWAS) was performed. Genotyping was conducted with the Illumina Human 610-Quad BeadChips array using DNAs from 618 Thai b0-thalassemia/HbE patients who were classified as 383 severe and 235 mild phenotypes by a validated scoring system. Twenty-three SNPs in three independent genes/regions were identified as being significantly associated with the disease severity. The highest association was observed with SNPs in the b-globin gene cluster (chr.11p15), and rs2071348 of the HBBP1 gene revealed the most significant association [P = 2.96 9 10(-13), odds ratio (OR) = 4.33 (95% confidence interval (CI), 2.74-6.84)]. The second was identified in the intergenic region between the HBS1L and MYB genes (chr.6q23), among which rs9376092 was the most significant [P = 2.36 9 10(-10), OR = 3.07 (95% CI, 2.16-4.38)]. The third region was located in the BCL11A gene (chr.2p16.1), and rs766432 showed the most significant association [P = 5.87 9 10-10, OR = 3.06 (95% CI, 2.15-4.37)]. All three loci were replicated in an independent cohort of 174 Indonesian patients. The associations to fetal hemoglobin levels were also observed with SNPs on these three regions. Our data indicate that several genetic loci act in concert to influence HbF levels of beta(0)-thalassemia/HbE patients. This study revealed that all the three reported loci and the alpha-globin gene locus are the best and common predictors of the disease severity in beta-thalassemia.

intermediate patients show a remarkable clinical heterogeneity. We examined the phenotypic diversity of 950 b-thalassemia/Hb E patients in an attempt to construct a system for classifying disease severity. A novel scoring system based on six independent parameters, hemoglobin level, age at disease presentation, age at receiving first blood transfusion, requirement for transfusion, spleen size, and growth and development, was able to separate patients into three distinctive severity categories: mild, moderate, and severe courses. This system, therefore, can increase the accuracy of studies of genotype-phenotype interactions and facilitate decisions for appropriate patient management. Am. J. Hematol. 83:482-484, 2008. V

No abstract

Alpha-thalassaemia 1 genetic disorder occurs when there is a deletion of two linked alpha-globin genes. The interaction between these abnormal genes leads to the most severe type of thalassaemia disease, haemoglobin (Hb) Bart's hydrops fetalis. The identification of alpha-thalassaemia 1 carriers and genetic counselling are essential for the prevention and control of severe thalassaemia diseases. In this study, we have developed a rapid screening method for identifying alpha-thalassaemia 1. A sandwich-type immunochromatographic (IC) strip test was developed, using the generated monoclonal anti-Hb Bart's antibody, to trace the Hb Bart's in haemolysates. When assayed by our IC strip test, all alpha-thalassaemia 1, HbH disease, HbH-Constant Spring (H-CS) disease, HbH-CS and heterozygous HbE (CSEA) Bart's disease, and homozygous alpha-thalassaemia 2 showed positive results. No false negative results were observed in these blood samples. In alpha-thalassaemia 2 heterozygotes, 83% of them showed positive reactivity. Among HbE (both homozygotes and heterozygotes), beta-thalassaemia (heterozygotes, homozygotes and beta-thalassaemia/HbE) and normal subjects, the IC strip test revealed negative reactivity of 100, 85 and 97%, respectively. These results indicate that this novel immunodiagnostic kit, in combination with red blood cell indices, is suitable for screening and ruling out mass populations for the presence of alpha-thalassaemia 1.

beta-Thalassemia/Hb E patients show a range of clinical severities, from nearly asymptomatic to transfusion-dependent thalassemia major. This study investigated the clinical heterogeneity and hematologic parameters obtained in the large cohort of 925 Thai beta 0-thalassemia/Hb E patients. Coinheritance of alpha-thalassemia with beta 0-thalassemia/Hb E produces a milder clinical phenotype in contrast to an interaction of alpha-globin gene triplication in severe thalassemia. The mean steady-state Hb was also higher, whereas the mean corpuscular volume and the percentage of Hb F were markedly lower in the former group. This finding demonstrates that the genetic combination leading to the more/less degree of alpha- to non-alpha-globin chains imbalance is indeed the cause of the severe/mild thalassemia phenotype.

No abstract

␣-Thalassemia is an inherited hemoglobin disorder that results from defective synthesis of ␣-globin protein. Couples who both carry the ␣-thalassemia-1 gene are at risk of having a fetus with Hb Bart's hydrops fetalis. Rapid and accurate screening for individuals carrying the ␣-thalassemia-1 gene is the most effective strategy to prevent and control this severe form of thalassemia. In this study , a new and accurate method for ␣-thalassemia diagnosis was developed by genotyping ␣-thalassemia-1, the Southeast Asian type (؊؊ SEA ) and Thai type (؊؊ THAI ) deletions, using multiplex PCR followed by a melting curve analysis. Primers were designed to specifically amplify two deletion fragments , the ؊؊ SEA and ؊؊ THAI deletions and two normal fragments , -and ␣2-globin gene. The primers were capable of distinguishing ␣-thalassemia 1 heterozygotes from ␣-thalassemia 2 homozygotes, which are unable to be diagnosed by standard hematological data and hemoglobin typing. The melting temperatures of the ؊؊ THAI , ؊؊ SEA , -globin, and ␣2-globin gene fragments were 79.9 ؎ 0.2 , 89.4 ؎ 0.5, 92.8 ؎ 0.2 , and 85.0 ؎ 0.2°C , respectively. Melting curve analysis was performed in 130 subjects in parallel with conventional gap-PCR analysis , and results showed 100% concordance. This method eliminates the post-PCR electrophoresis process , which is laborious , and allows high throughput screening suitable for large population screening for prevention and control

Hemoglobin E (Hb E)-beta-thalassemia patients display a range of clinical severities, from nearly asymptomatic to transfusion-dependent thalassemia major. Given this clinical heterogeneity, additional genetic factors modifying disease severity remain to be discovered. Association studies are being conducted to elucidate the role of genetic polymorphisms as disease severity modifiers in Hb E-beta-thalassemia patients. Using strict scoring criteria, 1060 Hb E-beta-thalassemia patients were categorized into mild, moderate, and severe groups. Taking a candidate gene approach, we found no statistically significant differences between the mild and severe patients groups in allelic or genotypic frequencies for single nucleotide polymorphisms within five genes known to influence globin gene expression and erythropoiesis.