The influence of the BCL11A polymorphism on the phenotype of patients with beta thalassemia could be affected by the beta globin locus control region and/or the Xmn1-HBG2 genotypic background

The Effect of Ferritin Level and Gene Expression of β-globin Promoter with β-thalassemia Patients in Al-Qadisiyah Governorate, Iraq

BACKGROUND:

The genetic condition β-thalassemia causes a deficit in the β-globin chain. Goblins are produced under the supervision of at least nine different genes. Thalassemia can be distinguished from other disorders by changes in these genes, which can lead to issues with hemoglobin synthesis. A typical side effect of thalassemia syndromes is iron overload, which raises the risk of mortality and can cause organ damage. Blood ferritin levels as well as total iron of body reserves have a positive correlation when there is no inflammation.

OBJECTIVE:

The purpose of this study was to assess the ferritin level of an Iraqi patient and the relationship between β-thalassemia and gene expression of β-globin.

MATERIALS AND METHODS:

A case–control study included 60 samples with mean age (17.76 ± 0.88; 28 males and 32 females) which had been collected from patients who were diagnosed with β-thalassemia and 60 samples with mean age (22.7 ± 0.75; 29 males, 31 females) which were collected from apparently healthy individuals as a control group (CG). The procedure’s outcome is monitored using polymerase chain reaction and the Fluorecare instrument.

RESULTS:

Ferritin levels in thalassemia patients were higher than in CG patients. The β-globin expression in the thalassemia group was significantly lower than in the CG. The discovery of two essential sequences thymine-adenine-thymine-adenine and cytosine-adenine-thymine-adenine in the β-gene promoter that are crucial in the start of transcription can account for this downregulation. Changes made to these sequences decreased the affinity of transcription factors, which in turn restricted the transcription of the messenger ribonucleic acid. Examples of these transcription factors are erythroid Kruppel-like factor and specificity protein 1.

CONCLUSION:

Ferritin can be a useful indicator of severe iron overload. The results showed that the level of expression of β-globin was dramatically downregulated within the thalassemia group as compared with the CG future prospective of this study.

The Impact of BCL11A Polymorphisms on Endometrial Cancer Risk Among Chinese Han Females

Background

Endometrial carcinoma (EC) is one of the most common malignant gynecological malignancies. BCL11A gene may have a tumor-suppressor role in EC. Until now, no studies have reported the effect of BCL11A variants on EC predisposition in Chinese population.

Methods

Six BCL11A polymorphisms were genotyped using Agena MassARRAY system among 509 EC patients and 506 matched healthy women. Risk assessment of the BCL11A polymorphisms for EC risk was performed by calculating odds ratios (OR) with 95% confidence intervals (CI) through logistic regression models.

Results

We found that rs7581162 (OR = 1.29, p = 0.012), rs10189857 (OR = 1.26, p = 0.028), rs1427407 (OR = 1.30, p = 0.015), rs766432 (OR = 1.27, p = 0.025), and rs6729815 (OR = 1.32, p = 0.008) in BCL11A were associated with higher susceptibility to EC in Chinese Han women. Age and BMI stratified analysis displayed that the risk association between BCL11A variants and EC predisposition might be age- and BMI-dependent. Haplotype analysis revealed that A_rs10189857T_rs1427407 and G_rs10189857G_rs1427407 haplotypes were related to an increased risk of EC. MDR analysis indicated that rs1427407 was the most influential attributor on EC risk in the single-locus model, and the best combination was the two-locus model containing rs7581162 and rs766432.

Conclusion

Our study provided the first evidence that rs7581162, rs10189857, rs1427407, rs766432, and rs6729815 in BCL11A were risk factors for EC in Chinese Han women. These findings add our understanding of the role of BCL11A gene in EC pathogenesis.

BCL11A Polymorphism in Egyptian Children with β-Thalassemia: Relation to Phenotypic Heterogeneity

Fetal hemoglobin (HbF) is a potent genetic modifier of β-thalassemia phenotype. B-cell lymphoma 11A ( BCL11A ) gene results in significant silencing of HbF. The aim of this study was to assess the prevalence of different BCL11A genotypes among a cohort of Egyptian children with β-thalassemia and to correlate them to HbF and clinical severity score. Eighty-two children with β-thalassemia (aged 12.95 ± 3.63 years) were recruited from the Pediatric Hematology Clinic, Ain Shams University. They were divided based on the clinical severity of β-thalassemia into three subgroups: 20 mild (24.4%), 24 moderate (29.3%), and 38 severe (46.3%). Age, gender, age of diagnosis, initial HbF level, transfusion history, and history of splenectomy were assessed. Anthropometric measures, signs of anemia and hemosiderosis, and the severity score were determined. Laboratory investigations such as complete blood picture, ferritin, and single gene polymorphism genotyping of the rs11886868 were also performed. Our findings showed that 16 children had CC genotype (19.5%), 38 had TC genotype (46.3%), and 28 had TT genotype (34.1%) of the rs#. β-thalassemia children with TT genotype had significantly higher severity scoring than the other two groups ( p  < 0.001). Moreover, mean initial HbF was found to be lower in children with TT genotype followed by TC and CC genotypes ( p  < 0.001). Increased γ-globin expression associated with BCL11A gene polymorphism is associated with better clinical severity of β-thalassemia.

Omics Studies in Hemoglobinopathies

Hemoglobinopathies include all genetic diseases of hemoglobin and are grouped into thalassemia syndromes and structural hemoglobin variants. The β-thalassemias constitute a group of severe anemias with monogenic inheritance, caused by β-globin gene mutations. This review is focused on omics studies in hemoglobinopathies and mainly β-thalassemia, and discusses genomic, epigenomic, transcriptomic, proteomic and metabolomic findings. Omics analyses have identified various disease modifiers with an impact on disease severity and efficacy of treatments. These modifiers have contributed to the understanding of globin genes regulation/hemoglobin switching and the development of novel therapies. How omics data and their integration can contribute to efficient patient stratification, therapeutic management, improvements in existing treatments and application of novel personalized therapies is discussed.

Pharmacoproteomics Profiling of Plasma From β-Thalassemia Patients in Response to Hydroxyurea Treatment

β-Thalassemia is a genetic disorder caused by defects in the β-globin gene resulting in the absence or reduced synthesis of adult hemoglobin (HbA). Hydroxyurea is an effective drug to increase fetal γ-globin (HbF) expression, replacing the missing adult β-globin. The mechanism of HbF induction by hydroxyurea and improvement in clinical symptoms are still poorly understood. In the present study we performed comparative analysis of plasma proteome in pre- and post-hydroxyurea-treated β-thalassemia major transfusion-dependent children (n = 10, mean age = 3.2 years) as well as responders versus nonresponders to hydroxyurea treatment. Plasma was collected before and after 6 months of hydroxyurea treatment, with patients subcategorized on the basis of their response to hydroxyurea. Among 400 identified proteins using a label-free quantitative proteomics approach, 28 proteins were found to be significantly different in pre- versus post-hydroxyurea-treated groups, with transferrin receptor protein-1 being most downregulated and hemopexin and haptoglobin the most upregulated proteins after treatment. In responder versus nonresponder comparison, 26 proteins were found to be differentially expressed, with carbonic anhydrase 1, hemoglobin subunit γ-1, and peroxiredoxin-2 showing the significant changes. The mechanism of hydroxyurea treatment in β-thalassemia patients appears to be complex, requiring a large sample size and a longer period of treatment to reveal its details.

Association of BCL11A genetic variant (rs11886868) with severity in β-thalassaemia major & sickle cell anaemia

Background & objectives:

The amount of foetal haemoglobin that persists in adulthood affects the clinical severity of haemoglobinopathies including β-thalassaemia major and sickle cell anaemia (SCA). The present study was undertaken to analyse β-thalassaemia as well as SCA patients for the single nucleotide polymorphism (SNP), rs11886868 (T/C) in BCL11A gene and to evaluate the association between this polymorphism and severity of β-thalassaemia major and SCA.

Methods:

A total of 620 samples (420 β-thalassaemia major and 200 SCA cases) were analysed before blood transfusion using basic screening tests like complete blood analysis and osmotic fragility and further confirmed by high performance liquid chromatography (HPLC), amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and reverse dot blot techniques. All patients were transfusion dependent. Patients with β-thalassaemia and SCA were classified into mild, moderate, severe according to the severity score based on Hb levels, age of onset, age at which patients received their first blood transfusion, the degree of growth retardation and splenectomy. β-thalassaemia as well as SCA patients were analysed for the SNP, rs11886868 (T/C) in BCL11A gene and association between this polymorphism and severity of β-thalassaemia major as well as SCA was evaluated.

Results:

There was a significant difference in genotypic and allelic frequencies of BCL11A gene polymorphism between mild and moderate and mild and severe cases in both the groups. A significant (P<0.001) difference was observed in the mean HbF levels between the three genotypes in different severity groups. HbF levels were found to be high in CC genotype bearing individuals followed by TC and TT in β-thalassaemia major as well as SCA.

Interpretation & conclusions:

This study confirms that the T/C variant (rs11886868) of the BCL11A gene causing downregulation of BCL11A gene expression in adult erythroid precursors results in the induction of HbF and ameliorates the severity of β-thalassaemia as well as SCA.

The Impact of XmnI-HBG2, BCL11A and HBS1L-MYB Single Nucleotide Polymorphisms on Hb F Variation of Hematologically Normal Iranian Individuals

The impact of Hb F on severity of sickle cell disease and β-thalassemia (β-thal) is well documented. The XmnI-HBG2, BCL11A and HBS1L-MYB single nucleotide polymorphisms (SNPs) have been introduced as the most important factors causing variation in fetal hemoglobin (Hb F) levels in different population studies. However, the extent of their effect could be population-specific. In this study, multivariate linear regression analysis was used to evaluate the association of Hb F with age, sex, and eight SNPs, including XmnI-HBG2, four BCL11A, two HBS1L-MYB SNPs and the polymorphic palindromic 5' hypersensitive 4-locus control region (5'HS4-LCR). One hundred and twenty-two hematologically normal individuals, from a previous study cohort, constituted our study population. In multivariate regression analyses, no association of Hb F was observed with age or sex of the individuals and SNPs in this study. We conducted a univariate regression analysis to further investigate the results, which among all the factors only detected XmnI-HBG2 and 5'HS4 SNPs as significant modifiers of Hb F. The significance of these two factors disappeared in a bivariate analysis. These results suggest that either XmnI-HBG2 or 5'HS4-LCR have a stronger contribution in Hb F variations of the Iranian population than BCL11A and HBS1L-MYB SNPs. Furthermore, the effect of low population size and technical limitations on obtained results could not be ruled out.

Current and future alternative therapies for beta-thalassemia major

Beta-thalassemia is a group of frequent genetic disorders resulting in the synthesis of little or no β-globin chains. Novel approaches are being developed to correct the resulting α/β-globin chain imbalance, in an effort to move beyond the palliative management of this disease and the complications of its treatment (e.g. life-long red blood cell transfusion, iron chelation, splenectomy), which impose high costs on healthcare systems. Three approaches are envisaged: fetal globin gene reactivation by pharmacological compounds injected into patients throughout their lives, allogeneic hematopoietic stem cell transplantation (HSCT), and gene therapy. HSCT is currently the only treatment shown to provide an effective, definitive cure for β-thalassemia. However, this procedure remains risky and histocompatible donors are identified for only a small fraction of patients. New pharmacological compounds are being tested, but none has yet made it into common clinical practice for the treatment of beta-thalassemia major. Gene therapy is in the experimental phase. It is emerging as a powerful approach without the immunological complications of HSCT, but with other possible drawbacks. Rapid progress is being made in this field, and long-term efficacy and safety studies are underway.