The Effect of Xmn -1 Polymorphism and Coinheritance of Alpha Mutations on Age at First Blood Transfusion in Iranian Patients with Homozygote IVSI-5 Mutation.

Background : Thalassemia syndromes are the most prevalent hereditary hemoglobinopathies in the world. Iran is located on the thalassemia belt.  In this study, the effect of Xmn -1 polymorphism and coinheritance of alpha mutations on age at first transfusion and also transfusion interval in Iranian thalassemic patients with homozygous IVSI-5 mutation were assessed. Materials and Methods : In this retrospective cross-sectional study 154 transfusion dependent thalassemia (TDT) patients (140 patients with ß-thalassemia major and 14 cases with ß-thalassemia intermedia) who were homozygote of IVSI-5 mutation have been participated. Blood samples were collected from participants using EDTA containers for genomic DNA analysis. DNA extraction and amplification-refractory mutation to determine the Xmn -1 polymorphism were performed. Multiplex PCR was performed to identify alpha globin deletions.  Results: The mean age of participants was 29±7, 58 of them were male and 96 were female. A significant relation between presence of Xmn -1 polymorphism and age at receiving first transfusion was detected. Coinheritance of alpha thalassemia mutation does not have significant effect on age at first transfusion or transfusion interval. Conclusion : Presence of Xmn -1 polymorphism can delay the onset of transfusion in patients with homozygote IVSI-5 mutation.

Laboratory diagnosis for thalassemia intermedia: Are we there yet?

BACKGROUND: Differentiation between thalassemia major and thalassemia intermedia at presentation is not uniformly characterized, for which an absolute criteria needs to be developed. This study investigated the primary and secondary genetic modifiers to develop a laboratory finding by forming different genetic mutational combinations seen among thalassemia intermedia patients and comparing them with thalassemia major. METHODS: This cross-sectional study analyzed 315 thalassemia intermedia patients. One hundred and five thalassemia major patients were recruited on the basis of documented evidence of diagnosis and were receiving blood transfusion therapy regularly. Various mutational combinations were identified, and comparison was performed between thalassemia intermedia and major using statistical software STATA 11.1. RESULTS: The mean age of the total population was 5.9 ± 5.32 years of which 165 (52%) were males. Of the two groups (thalassemia intermedia and thalassemia major), IVSI-5, IVSI-1, and Fr 8-9 were more prevalent among the thalassemia intermedia cohort. When comparison was performed between the thalassemia intermedia and thalassemia major patients, it showed significant results for the presence of Xmn-1 polymorphism. CONCLUSION: The presence of IVSI-5 homozygous with Xmn-1, IVSI-5 heterozygous with Xmn-1, Cd 30 homozygous with or without Xmn-1 and IVSI-1 homozygous or heterozygous either with or without Xmn-1 prove to be strong indicators towards diagnosis of thalassemia intermedia.

Genetic determinants related to pharmacological induction of foetal haemoglobin in transfusion-dependent HbE-ß thalassaemia.

Thalassaemia are the most common inherited autosomal recessive single gene disorders characterized by chronic hereditary haemolytic anaemia due to the absence or reduced synthesis of one or more of the globin chains. Haemoglobin E-ß thalassaemia is the genotype responsible for approximately one half of all severe beta-thalassaemia worldwide. This study proposes to evaluate the effect of various molecular parameters on the response of hydroxyurea. Hydroxyurea was started at an initial dose of 10 mg/kg of body weight/day on 110 transfusion-dependent HbE-ß thalassaemia patients. HbF level was measured by HPLC analysis. ß-Thalassaemia mutations, XmnI and five other SNPs, and α-globin gene deletions and triplications were detected by ARMS-PCR, RFLP-PCR and Gap-PCR, respectively. Based on the factors for evaluating hydroxyurea-response, 42 patients were responders as they showed an increment of Hb from a mean baseline value of 6.45 g/dl (± 0.70) to 7.78 g/dl (± 0.72) post-therapy. Based on increase in HbF above the median value (14.72%) post-therapy, 78 patients were found to be responders. All the 78 responders showed mean decrease in transfusion of 74.26% (± 8.32) with a maximum decrease of 98.43%. There was a significant correlation between decrease in transfusion and increase in HbF level for all 78 responders. XmnI polymorphism showed the strongest association (p < 0.0001) with increase in HbF levels and Hb levels. Patients with α-globin gene deletions were better responders. It was concluded that hydroxyurea treatment is effective in transfusion-dependent HbE-ß thalassaemia patients and the response is best in patients having both XmnI polymorphism and α-deletion.

Xmn1-158 γGVariant in B-Thalassemia Intermediate Patients in South-East of Iran.

Background: Xmn-1 polymorphism of 𝜸Gglobin gene (HBG2) is a prominent quantitative trait loci (QTL) in ß-thalassemia intermediate (ß-TI). In current study, we evaluated the frequency of Xmn-1 polymorphism and its association with ß-globin gene (HBB) alleles and Hb F level in ß-TI patients in Sistan and Balouchestan province, south-east of Iran. Subjects and Methods: 45 ß-TI patients were enrolled. HBB gene mutations and Xmn-1 polymorphism were determined by amplification-refractory mutation system (ARMS) PCR method. Hemoglobin profile was determined using capillary electrophoresis. Results: The study participants consisted of 26 (58%) males and 19 (42%) females. Mean age of the patients was 10.7±3.1 years old. Overall, Xmn-1 polymorphism was observed in 28 (62%) patients. Homozygous (TT) and heterozygous (CT) genotypes of the polymorphism represented with frequencies of 12 (26%) and 16 (35%), respectively. Main recognized HBB gene mutation was IVSI-5(G>C) with homozygous frequency of 44%. Non-zero (ß+) alleles of HBB gene constituted 11.1 % (4 patients with heterozygous ß+ and one with homozygous ß+ genotype). Hb F level was significantly higher in patients with at least one Xmn-1allele (67.9±[Formula: see text]17.9%) than those without the polymorphism (19.5±20.3%, P<0.0001). Also, patients with homozygous genotype demonstrated significantly higher Hb F compared to heterozygous (CT) cases (respective percentages of 85±[Formula: see text]6.8 and 54.7±[Formula: see text]10.5, p<0.0001). Conclusion: Our results highlighted the role of Xmn-1 polymorphism as the main phenotypic modifier in ß-TI patients in Sistan and Balouchestan province.

A Large Cohort Study of Genotype and Phenotype Correlations of Beta- Thalassemia in Iranian Population.

BACKGROUND: Thalassemia syndromes are the most prevalent single gene disorders in Iran. This study aimed to evaluate the effect of different types of beta-globin gene mutations, co-inheritance of alpha-globin gene mutations and/or Xmn1 SNP on disease phenotype in a large cohort of Iranian patients. SUBJECTS AND METHODS: In total, 433 patients were clinically classified into ß-thalassemia major (TM) or intermedia (TI). Multiplex PCR, ARMS-PCR, RFLP-PCR and DNA sequencing were performed to identify both α- and ß-globin gene mutations and Xmn1 polymorphism as well. All data were compared and analyzed by SPSS software in TM and TI groups, consequently. RESULTS: A total of 39 different ß-globin mutations were identified. Among them, the most common were IVS IInt1 (40.33%) followed by IVS Int5 (9.56%), C30 (7.22%) and Fr8-9(7%). All patients were subjected to evaluate common α-globin gene deletions. The patients inherited concomitant mutations of α- and ß-globin, showed no clinical modifications compared with those who had only ß-globin mutation. The TI patients showed a significant increase in frequency of both heterozygous and homozygous form of the Xmn1 polymorphism. It was also found that ß(0)/ß(0) genotype patients, inherited the Xmn1 polymorphism required lesser blood transfusion. CONCLUSION: No significant differences were observed, on the severity of disease, between patient's inherited defective α- and ß-globin genes and ones with just ß-globin gene mutation. Taking the results of this research into account, Xmn1 polymorphism can be considered as an important genetic factor modulating the severity of disease.