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Molecular characterisation of sickle cell disease and classification of major haplotypes associated with the β-globin cluster ( HBB gene) by means of SNP marker sequencing in a group of samples from Bolívar, Colombia. Ann Hum Biol 2024; 51:2308714. [PMID: 38378484 DOI: 10.1080/03014460.2024.2308714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 01/08/2024] [Indexed: 02/22/2024]
Abstract
BACKGROUND Colombia has a mestizo population and the prevalence of haemoglobin variants varies according to each region, but heterozygous carriers can be found in all of them. AIM To characterise sickle cell disease (SCD) haematologically, biochemically, and molecularly, and detect classic haplotypes by DNA sequencing in a group of samples from Bolívar, Colombia. SUBJECTS AND METHODS Blood samples were collected after informed consent from volunteers from eight communities in the Bolívar department, plus samples from the Pacific region, Providencia Island, and Bogotá were included. Data were obtained from: (1) haematological analyses; (2) biochemical tests: dHPLC was used to determine haemoglobin (Hb); and (3) DNA sequencing data through five SNPs. RESULTS 101 samples were identified by rs334 through Sanger's Sequencing, structural haemoglobinopathies HbAS (34.65%), HbSS (2.97%) and HbAC (1.98%) were found. When contrasting the Hb identification results between SNP rs334 Vs. dHPLC/Isoelectric Focusing (IEF), a coincidence was found in 39/43 samples analysed, therefore, when comparing these techniques, a significant correlation was found (Pearson's correlation coefficient r = 0.998). 26 samples previously analysed by rs334 were classified into classical haplotypes CAR (50.0%), BEN (30.76%), CAM (7.69%), SEN (3.84%), and ATP-I (7.69%). CONCLUSIONS SCD characterisation and SNPs-based classification through Sanger's DNA sequencing have not been performed before in Colombia. The results of this work will make it possible to expand the data or records of carriers and those affected, which will benefit patients and their families.
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Identification of a Novel Variant c.163delG in HBB Gene Resulting in a Beta Null Phenotype in a Proband with Thalassemia Intermedia. Hemoglobin 2024; 48:1-3. [PMID: 38258429 DOI: 10.1080/03630269.2023.2279609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 10/31/2023] [Indexed: 01/24/2024]
Abstract
A 21-year-old patient presented with a previous medical history of pallor, mild icterus, increased fatigue, low hemoglobin, and abnormal hemoglobin variant analysis with more than 70 transfusions. He was referred for genetic analysis to identify the pathogenic variations in the β-globin gene. Sanger's sequencing of the proband and his family revealed the presence of a novel frame shift variant HBB:c.163delG in a compound heterozygous state with hemoglobin E (HbE) (HBB:c.79G > A) variant. The father and the sibling of the patient were found to be normal for the HBB gene. Mother was found to be heterozygous for HbE (HBB:c.79G > A) variant. In silico analysis by Mutalyzer predicted that c.163delG variant generated a premature stop codon after seven codons, leading to a truncated protein. FoldX protein stability analysis showed a positive ΔΔG value of 45.27 kcal/mol suggesting a decrease in protein stability. HBB:c.79G > A is a known variant coding for HbE variant, which results in the reduced synthesis of β-globin chain and shows mild thalassemia. Combined effect of HBB:c.163delG and HBB:c.79G > A variants in the proband might have led to the reduced synthesis of β-globin chains resulting in a thalassemia intermedia type of clinical manifestation.
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Molecular dynamics of genome editing with CRISPR-Cas9 and rAAV6 virus in human HSPCs to treat sickle cell disease. Mol Ther Methods Clin Dev 2023; 30:317-331. [PMID: 37637384 PMCID: PMC10447934 DOI: 10.1016/j.omtm.2023.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 07/25/2023] [Indexed: 08/29/2023]
Abstract
Ex vivo gene correction with CRISPR-Cas9 and a recombinant adeno-associated virus serotype 6 (rAAV6) in autologous hematopoietic stem/progenitor cells (HSPCs) to treat sickle cell disease (SCD) has now entered early-phase clinical investigation. To facilitate the progress of CRISPR-Cas9/rAAV6 genome editing technology, we analyzed the molecular changes in key reagents and cellular responses during and after the genome editing procedure in human HSPCs. We demonstrated the high stability of rAAV6 to serve as the donor DNA template. We assessed the benefit of longer HSPC pre-stimulation in terms of increased numbers of edited cells. We observed that the p53 pathway was transiently activated, peaking at 6 h, and resolved over time. Notably, we revealed a strong correlation between p21 mRNA level and rAAV6 genome number in cells and beneficial effects of transient inhibition of p53 with siRNA on genome editing, cell proliferation, and cell survival. In terms of potential immunogenicity, we found that rAAV6 capsid protein was not detectable, while a trace amount of residual Cas9 protein was still detected at 48 h post-genome editing. We believe this information will provide important insights for future improvements of gene correction protocols in HSPCs.
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Mutation Spectrum of β-Thalassemia in Some Ethnic Groups of North Maharashtra, India. Hemoglobin 2023:1-6. [PMID: 37381791 DOI: 10.1080/03630269.2023.2212911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Beta-thalassemia is the most common inherited single-gene disorder in the world, caused by more than 200 known mutations in the HBB gene. In India, the average prevalence of β-thalassemia carriers is 3-4%. Several ethnic groups have a much higher prevalence, about 8% in the tribal groups, according to the 2011 census. The study's main goal is to identify common β-thalassemia mutations and the frequencies of different haplotypes in various communities in North Maharashtra. Nashik district had the highest prevalence of β-thalassemia (34%), followed by Ahmednagar (29%), Jalgaon (16%), Dhule (14%), and Nandurbar (7.0%). Prevalence of β-thalassemia was highest in the schedule caste community (SC) (48%), followed by (17%) in Muslims, (14%) in other backward classes (OBC), (13%) in Schedule Tribe (ST), and (8.0%) in the general population The six most common β-thalassemia mutations detected in this study are IVS 1 > 5 (G→C), Cd 15(G→A), Cd 41/41 (-TCTT), Cd 8/9(+G), IVS 1 > 1(G→T) and Cap + 1(A > G). Among these mutations, IVS 1 > 5 (G > C) was the most common type of mutation found in β-thalassemia patients in the North Maharashtra population. Type-I haplotype was the most prevalent among all communities. Nashik and Ahmednagar districts were highly affected by β-thalassemia. Among different ethnic groups, the SC and Muslim communities were the worst affected with a higher proportion of β-thalassemia and increased frequency of mutations.
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Five Years' Experience with Gene Panel Sequencing in Hereditary Hemolytic Anemia Screened by Routine Peripheral Blood Smear Examination. Diagnostics (Basel) 2023; 13:diagnostics13040770. [PMID: 36832257 PMCID: PMC9954878 DOI: 10.3390/diagnostics13040770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND Hereditary hemolytic anemia (HHA) is defined as a group of heterogeneous and rare diseases caused by defects of red blood cell (RBC) metabolism and RBC membrane, which leads to lysis or premature clearance. The aim of this study was to investigate individuals with HHA for potential disease-causing variants in 33 genes reported to be associated with HHA. METHODS A total of 14 independent individuals or families diagnosed with suspected HHA, and in particular, RBC membranopathy, RBC enzymopathy, and hemoglobinopathy, were collected after routine peripheral blood smear testing. A custom designed panel, including the 33 genes, was performed using gene panel sequencing on the Ion Torrent PGM™ Dx System. The best candidate disease-causing variants were confirmed by Sanger sequencing. RESULTS Several variants of the HHA-associated genes were detected in 10 out of 14 suspected HHA individuals. After excluding those variants predicted to be benign, 10 pathogenic variants and 1 variant of uncertain significance (VUS) were confirmed in 10 individuals with suspected HHA. Of these variants, the p.Trp704Ter nonsense variant of EPB41 and missense p.Gly151Asp variant of SPTA1 were identified in two out of four hereditary elliptocytoses. The frameshift p.Leu884GlyfsTer27 variant of ANK1, nonsense p.Trp652Ter variant of the SPTB, and missense p.Arg490Trp variant of PKLR were detected in all four hereditary spherocytosis cases. Missense p.Glu27Lys, nonsense p.Lys18Ter variants, and splicing errors such as c.92 + 1G > T and c.315 + 1G > A within HBB were identified in four beta thalassemia cases. CONCLUSIONS This study provides a snapshot of the genetic alterations in a cohort of Korean HHA individuals and demonstrates the clinical utility of using gene panels in HHA. Genetic results can provide precise clinical diagnosis and guidance regarding medical treatment and management for some individuals.
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Clinical genome editing to treat sickle cell disease-A brief update. Front Med (Lausanne) 2023; 9:1065377. [PMID: 36698803 PMCID: PMC9868311 DOI: 10.3389/fmed.2022.1065377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 12/14/2022] [Indexed: 01/10/2023] Open
Abstract
Sickle cell disease (SCD) is one of the most common hemoglobinopathies. Due to its high prevalence, with about 20 million affected individuals worldwide, the development of novel effective treatments is highly warranted. While transplantation of allogeneic hematopoietic stem cells (HSC) is the standard curative treatment approach, a variety of gene transfer and genome editing strategies have demonstrated their potential to provide a prospective cure for SCD patients. Several stratagems employing CRISPR-Cas nucleases or base editors aim at reactivation of γ-globin expression to replace the faulty β-globin chain. The fetal hemoglobin (HbF), consisting of two α-globin and two γ-globin chains, can compensate for defective adult hemoglobin (HbA) and reverse the sickling of hemoglobin-S (HbS). Both disruption of cis-regulatory elements that are involved in inhibiting γ-globin expression, such as BCL11A or LRF binding sites in the γ-globin gene promoters (HBG1/2), or the lineage-specific disruption of BCL11A to reduce its expression in human erythroblasts, have been demonstrated to reestablish HbF expression. Alternatively, the point mutation in the HBB gene has been corrected using homology-directed repair (HDR)-based methodologies. In general, genome editing has shown promising results not only in preclinical animal models but also in clinical trials, both in terms of efficacy and safety. This review provides a brief update on the recent clinical advances in the genome editing space to offer cure for SCD patients, discusses open questions with regard to off-target effects induced by the employed genome editors, and gives an outlook of forthcoming developments.
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Genetic correction of concurrent α- and β-thalassemia patient-derived pluripotent stem cells by the CRISPR-Cas9 technology. Stem Cell Res Ther 2022; 13:102. [PMID: 35255977 PMCID: PMC8900422 DOI: 10.1186/s13287-022-02768-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/15/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Thalassemia is a genetic blood disorder characterized by decreased hemoglobin production. Severe anemia can damage organs and severe threat to life safety. Allogeneic transplantation of bone marrow-derived hematopoietic stem cell (HSCs) at present represents a promising therapeutic approach for thalassemia. However, immune rejection and lack of HLA-matched donors limited its clinical application. In recent years, human-induced pluripotent stem cells (hiPSCs) technology offers prospects for autologous cell-based therapy since it could avoid the immunological problems mentioned above. METHODS In the present study, we established a new hiPSCs line derived from amniotic cells of a fetus with a homozygous β41-42 (TCTT) deletion mutation in the HBB gene and a heterozygous Westmead mutation (C > G) in the HBA2 gene. We designed a CRISPR-Cas9 to target these casual mutations and corrected them. Gene-corrected off-target analysis was performed by whole-exome capture sequencing. The corrected hiPSCs were analyzed by teratoma formation and erythroblasts differentiation assays. RESULTS These mutations were corrected with linearized donor DNA through CRISPR/Cas9-mediated homology-directed repair. Corrections of hiPSCs were validated by sequences. The corrected hiPSCs retain normal pluripotency. Moreover, they could be differentiated into hematopoietic progenitors, which proves that they maintain the multilineage differentiation potential. CONCLUSIONS We designed sgRNAs and demonstrated that these sgRNAs facilitating the CRISPR-Cas9 genomic editing system could be applied to correct concurrent α- and β-thalassemia in patient-derived hiPSCs. In the future, these corrected hiPSCs can be applied for autologous transplantation in patients with concurrent α- and β-thalassemia.
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First report of successful treatment for hemoglobin Bristol-Alesha by hemopoietic stem cell transplantation. Ann Hematol 2021; 101:617-619. [PMID: 34851438 DOI: 10.1007/s00277-021-04721-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 11/03/2021] [Indexed: 12/01/2022]
Abstract
HBB gene mutations lead to many kinds of diseases, of which, except for the two most common diseases of thalassemia and sickle cell anemia, rare kinds of hemolytic anemia, such as hemoglobin Bristol-Alesha, are rarely reported, no ideal treatment in clinic. A child suffered from chronic recurrent hemolytic attacks and the related genes of hereditary hemolytic anemia were detected on her. Hematopoietic stem cell transplantation was conducted in the treatment of the patient. The patient was diagnosed as hemoglobin Bristol-Alesha and achieved complete recovery after hematopoietic stem cell transplantation. For Bristol-Alesha, without characteristic clinical manifestation and specific biochemical examination, diagnosis is dependent on the gene mutation detection and hematopoietic stem cell transplantation is an effective and curable method.
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Elevated Hb A 2 is Not Always Indicative of β-Thalassemia. Hemoglobin 2021; 45:186-190. [PMID: 34100337 DOI: 10.1080/03630269.2021.1936008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Hb A2 levels are usually high in carriers of β-thalassemia (β-thal). These levels also provide a sensitive marker for the identification of hemoglobin (Hb) variants. In this study, we aimed to examine two patients from two Chinese families who showed elevated Hb A2 levels but did not show any signs of β-thal. The HBB variants were analyzed using direct sequencing of HBB and in silico prediction analysis. Moreover, the family's genetic history was investigated. We examined two probands from different Chinese families with elevated Hb A2 levels who were not afflicted with β-thal, although several nucleotide changes were found at codon 81 (CTC>CTA) (HBB: c.246C>A) in Family 1 and a compound heterozygosity for codon 40 (AGG>AAG) (HBB: c.122G>A) and IVS-II-478 (C>A) (HBB: c.316-373C>A) in Family 2. After investigating the genetic history of both families including the β-thal aspect, we found that these mutations were not responsible for the elevated Hb A2 levels. It is rarely reported that high Hb A2 level is not indicative of β-thal. In contrast, low or normal Hb A2 level is always found with β-thal due to other molecular defects that mask their β-thal genotype. Our results highlight the importance of considering the genetic factors related and unrelated to β-thal to improve the accuracy of future genetic counseling.
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Abstract
OBJECTIVES To investigate the mutational spectrum in the HBB gene in Arab patients with β-thal. METHODS Authors searched five databases (PubMed, Science Direct, Scopus, Web of Science, and Google Scholar) from the time of inception until March 2020. RESULTS The authors search strategy yielded 3,229 citations, of which 48 eligible studies captured. 105 mutations were captured, of these, 99 were shared between Arabs and other ethnic groups, six mutations were unique to Arabs (c.92 + 2 T > G, c.-240 G > A, c.150delC, c.420dupT, deletion of 192 bp spanning exon 1, intron 1, and the first two bases of exon 2 of HBB gene, and deletion of 9.6 kb, including exon 1 and intron 2 of HBB gene). The most common HBB gene mutations among Arabs were c.93-21 G > A, c.118 C > T, c.92 + 1 G > A, c.92 + 6 T > C, c.92 + 5 G > C, c.315 + 1 G > A, and c.27dupG. Consanguinity is high among Arab patients with β-thal. Migration into Arab countries led to allelic heterogeneity among Arab patients with β-thal. CONCLUSION Our findings present a platform for further genetic epidemiological studies for Arab patients with β-thal.
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Compound Heterozygosity for a Novel Mutation Codon 104 (-A) ( HBB: c.313delA) and Codons 41/42 (-CTTT) ( HBB: c.126_129delCTTT) Leading to β-Thalassemia Major in a Chinese Family. Hemoglobin 2020; 44:402-405. [PMID: 33198537 DOI: 10.1080/03630269.2020.1843482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
β-Thalassemia (β-thal) is a hereditary blood disorder characterized by the reduced or absent synthesis of β-globin chains. Here, we report a case of severe thalassemia with compound heterozygosity for a novel deletion mutation at codon 104 (-A) (HBB: c.313delA) and codons 41/42 (-CTTT) (HBB: c.126_129delCTTT) on the β-globin gene (HBB), and a coinheritance of the -α4.2 (leftward) deletion on the α-globin gene cluster. The proband was a 12-year-old boy, and four other family members were involved in this study. This novel frameshift mutation caused classical β-thal trait in the heterozygote and a transfusion-dependent form of β-thal major (β-TM) in compound heterozygosity with other β0 mutations.
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Detection of Paternal IVS-II-1 (G>A) ( HBB: c.315+1G>A) Mutation in Cell-Free Fetal DNA Using COLD-PCR assay. Hemoglobin 2020; 44:168-173. [PMID: 32703054 DOI: 10.1080/03630269.2020.1768864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Standardization of noninvasive prenatal diagnosis (PND) method that can identify common mutations in the population is of great value. The purpose of this study was to find the paternal HBB gene IVS-II-1 (G>A) (HBB: c.315+1G>A) mutation in maternal plasma cell-free DNA using the co-amplification at lower denaturation temperature-polymerase chain reaction (COLD-PCR) method. We designed simulated circulating free DNA (cfDNA) in maternal plasma to optimize the COLD-PCR assay. Peripheral blood samples were collected from normal and IVS-II-1 heterozygous individuals as well as five heterozygous pregnant women whose husbands were carriers of IVS-II-1. The cfDNA was extracted from the plasma and subjected to optimized COLD-PCR followed by Sanger sequencing. The optimized protocol was tested on simulated cfDNA samples with proportions of 8.0, 6.0, 4.0 and 2.0%, and the results showed that the COLD-PCR is informative on samples containing 8.0% mutant alleles and above. The patients were undergoing invasive PND procedures via chorionic villi sampling (CVS) as scheduled at the 12th week of gestation. Paternal IVS-II-1 was detected in cfDNA samples of three patients who were in complete concordance with the outcome of CVS. Despite the limitations of the COLD-PCR method in noninvasive PND, it can be considered as a cost-effective screening option. The use of this approach for screening at-risk patients can prevent unnecessary invasive procedures identifying common mutations in high-prevalence diseases.
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Noninvasive prenatal diagnosis for pregnancies at risk for β-thalassaemia: a retrospective study. BJOG 2020; 128:448-457. [PMID: 32363759 DOI: 10.1111/1471-0528.16295] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2020] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To evaluate the clinical feasibility of noninvasive prenatal diagnosis (NIPD) for β-thalassaemia using circulating single molecule amplification and re-sequencing technology (cSMART). DESIGN Through carrier screening, 102 pregnant Chinese couples carrying pathogenic HBB gene variants were recruited to the study. Pregnancies were managed using traditional invasive prenatal diagnosis (IPD). Retrospectively, we evaluated the archived pregnancy plasma DNA by NIPD to evaluate the performance of our cSMART assay for fetal genotyping. SETTING Chinese prenatal diagnostic centres specialising in thalassaemia testing. POPULATION Chinese carrier couples at high genetic risk for β-thalassaemia. METHODS Fetal cell sampling was performed by amniocentesis and HBB genotypes were determined by reverse dot blot. NIPD was performed by a newly designed HBB cSMART assay and fetal genotypes were called by measuring the allelic ratios in the maternal cell-free DNA. MAIN OUTCOME MEASURES Concordance of HBB fetal genotyping between IPD and NIPD and the sensitivity and specificity of NIPD. RESULTS Invasive prenatal diagnosis identified 29 affected homozygotes or compound heterozygotes, 54 heterozygotes and 19 normal homozygotes. Compared with IPD results, 99 of 102 fetuses (97%) were correctly genotyped by our NIPD assay. Two of three discordant samples were false positives and the other sample involved an incorrect call of a heterozygote carrier as a homozygote normal. Overall, the sensitivity and specificity of our NIPD assay was 100% (95% CI 88.06-100.00%) and 97.26% (95% CI 90.45-99.67%), respectively. CONCLUSIONS This study demonstrates that our cSMART-based NIPD assay for β-thalassaemia has potential clinical utility as an alternative to IPD for pregnant HBB carrier couples. TWEETABLE ABSTRACT A new noninvasive test for pregnancies at risk for β-thalassaemia.
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Functional polymorphisms of BCL11A and HBS1L-MYB genes affect both fetal hemoglobin level and clinical outcomes in a cohort of children with sickle cell anemia. Ann Hematol 2020; 99:1453-1463. [PMID: 32447424 DOI: 10.1007/s00277-020-04079-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 05/04/2020] [Indexed: 01/28/2023]
Abstract
Fetal hemoglobin (HbF) ameliorates clinical severity of sickle cell anemia (SCA). The major loci regulating HbF levels are HBB cluster, BCL11A, and HMIP-2 (HBS1L-MYB). However, the impact of noncoding single-nucleotide polymorphisms (SNPs) in these loci on clinical outcomes and their functional role on regulating HbF levels should be better elucidated. Therefore, we performed comprehensive association analyses of 14 noncoding SNPs in five loci with HbF levels and with clinical outcomes in a cohort of 250 children with SCA from Southeastern Brazil, and further performed functional annotation of these SNPs. We found SNPs independently associated with HbF levels: rs4671393 in BCL11A (β-coefficient = 0.28), rs9399137 in HMIP-2A (β-coefficient = 0.16), and rs4895441 in HMIP-2B (β-coefficient = 0.15). Patients carrying minor (HbF-boosting) alleles for rs1427407, rs93979137, rs4895441, rs9402686, and rs9494145 showed reduced count of reticulocytes (p < 0.01), while those carrying the T allele of rs9494145 showed lower white blood cell count (p = 0.002). Carriers of the minor allele for rs9402686 showed higher peripheral saturation of oxygen (p = 0.002). Patients carrying minor alleles in BCL11A showed lower risk of transfusion incidence rate ratio (IRR ≥ 1.3; p < 0.0001). This effect was independent of HbF effect (p = 0.005). Carriers of minor alleles for rs9399137 and rs9402686 showed lower risk of acute chest syndrome (IRR > 1.3; p ≤ 0.01). Carriers of the reference allele for rs4671393 showed lower risk of infections (IRR = 1.16; p = 0.01). In conclusion, patients carrying HbF-boosting alleles of BCL11A and HMIP-2 were associated with milder clinical phenotypes. Higher HbF concentration may underlie this effect.
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Identification of seven novel variants in the β-globin gene in transfusion-dependent and normal patients. Arch Med Sci 2020; 16:453-459. [PMID: 32190157 PMCID: PMC7069418 DOI: 10.5114/aoms.2019.84825] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 09/20/2018] [Indexed: 12/03/2022] Open
Abstract
INTRODUCTION Abnormality in HBB results in an inherited recessive blood disorder, which can be caused by variants at the transcriptional or translational level affecting the stability and the production of the HBB chain. The severity of the disease relies on the variant's characteristics. This study aimed to identify the common β-globin HBB variants in the population of the Eastern Province, which has the highest prevalence of blood diseases in Saudi Arabia. MATERIAL AND METHODS Direct sequence of β-globin HBB gene, and alpha-globin HBA1 and HBA2 genes was performed on a total of 545 blood samples (transfusion-dependent: 215, 106 men and 109 women; normal healthy subjects: 330, 197 men and 133 women) collected from Saudi Arabian participants in the Eastern region. RESULTS A total of 36 variants in HBB gene were revealed with 11 variants that have been reported for the first time in Saudi Arabia, including 7 novel variants that have been identified for the first time in HBB gene. The novel variants consisted of two exonic (HBB:c.252C>T; HBB:c.281G>T) and five intronic variants (c.316-183_316-168del; c.315+241T>A; c.315+376T>C; c.316-114C>G; c.315+208T>G) at HBB gene. The novel exonic variants and three (c.316-183_316-168del; c.315+241T>A; c.315+376T>C) intronic variants were co-inherited with α deletion. CONCLUSIONS This current study updated the HBB gene variations with newly identified variants of HBB gene and co-inheritance with α-globin deletions. The identified β-globin mutations will strengthen the genetic reference that could aid in characterizing mutations that are associated with phenotype of thalassemia in a specific region.
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Efficient gene correction of an aberrant splice site in β-thalassaemia iPSCs by CRISPR/Cas9 and single-strand oligodeoxynucleotides. J Cell Mol Med 2019; 23:8046-8057. [PMID: 31631510 PMCID: PMC6850948 DOI: 10.1111/jcmm.14669] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 08/15/2019] [Accepted: 08/18/2019] [Indexed: 12/19/2022] Open
Abstract
β‐thalassaemia is a prevalent hereditary haematological disease caused by mutations in the human haemoglobin β (HBB) gene. Among them, the HBB IVS2‐654 (C > T) mutation, which is in the intron, creates an aberrant splicing site. Bone marrow transplantation for curing β‐thalassaemia is limited due to the lack of matched donors. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR‐associated protein 9 (Cas9), as a widely used tool for gene editing, is able to target specific sequence and create double‐strand break (DSB), which can be combined with the single‐stranded oligodeoxynucleotide (ssODN) to correct mutations. In this study, according to two different strategies, the HBB IVS2‐654 mutation was seamlessly corrected in iPSCs by CRISPR/Cas9 system and ssODN. To reduce the occurrence of secondary cleavage, a more efficient strategy was adopted. The corrected iPSCs kept pluripotency and genome stability. Moreover, they could differentiate normally. Through CRISPR/Cas9 system and ssODN, our study provides improved strategies for gene correction of β‐Thalassaemia, and the expression of the HBB gene can be restored, which can be used for gene therapy in the future.
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Abstract
INTRODUCTION Elevated HbA2 (hemoglobin A2) level is considered the most reliable hematological parameter for the detection of β-thalassemia carriers. However, some carriers are difficult to recognize because the level of HbA2 is not in the distinctive carrier range, i.e. 4.0-6.0%; instead, some carriers have HbA2 levels between normal and carrier levels, i.e. borderline HbA2 (HbA2 = 3.1-3.9%). Studies have shown that variations in the erythroid Krüppel-like factor (KLF1) gene lead to borderline HbA2 in β-thalassemia carriers from various populations. The incidence of borderline HbA2 in Saudis is high. MATERIAL AND METHODS To confirm the influence of variations in KLF1, HBA1, HBA2 and HBB genes for the reduction of the level of HbA2 in Saudi β-thalassemia carriers, we performed a direct sequence analysis of KLF1, HBA1, HBA2 and HBB genes from 212 healthy Saudis (88 subjects: HbA2 < 3; 72 subjects: HbA2 = 3.1 to 3.9; 52 subjects HbA2 > 4.3). RESULTS The presence of the borderline HbA2 level is not specific to any type of β-thalassemia variation or β+-thalassemia variations in Saudis. Two exonic (c.304T>C and c.544T>C) and two 3' untranslated region (3'UTR) (c.*296G>A and c.*277C>G) variations have been identified in the KLF1 gene for the first time from an Arab population. None of these four variations in KLF1 genes are significantly associated with the Saudis with borderline HbA2. α Globin genotype, -α23.7/α1α2, is found to be the most frequent (55.55%) among healthy Saudis with borderline HbA2 compared with the other groups (HbA2 < 3 = 20.45%; HbA2 > 4.3 = 13.51%). CONCLUSIONS Further studies are necessary to determine the influence of other factors on the presence of borderline HbA2 in 41.67% of Saudis.
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Revisiting a Complex Rearrangement Involving a 619 Base Pairs Deletion, 6 Nucleotide Insertion Followed by a A > G Substitution Causing β°-Thalassemia. Indian J Hematol Blood Transfus 2016; 32:500-503. [PMID: 27812264 DOI: 10.1007/s12288-016-0682-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/09/2016] [Indexed: 11/29/2022] Open
Abstract
One of the prevalent inherited blood disorders is thalassemia syndrome that characterized by reduction (β+) or absence (β0) of β globin chain synthesis. The β globin (HBB) gene map in the short arm of chromosome 11 and most of the mutations in this gene are single nucleotide substitutions, insertions or deletions of nucleotides. Nucleotide sequence analysis of a partially deleted β-globin gene from an Iranian carrier of β-thalassemia displayed a complex rearrangement involving a 619 base pairs (bp) deletion. This rearrangement had originally been named as the 619 bp deletion and later on as the 619 bp deletion with a 7 bp insertion. In our study, using by single chain sequencing, we have shown that the actual rearrangement involves a 619 bp deletion, a 6 bp insertion followed by a G > A substitution deleting the exon 3 of the β-globin gene. This clarification has to be inserted into the relevant databases as some of them still site the original 619 bp deletion with wrong breakpoints.
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NO ASSOCIATION BETWEEN tHbmass AND POLYMORPHISMS IN THE HBB GENE IN ENDURANCE ATHLETES. Biol Sport 2014; 31:115-9. [PMID: 24899775 PMCID: PMC4042665 DOI: 10.5604/20831862.1099372] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2014] [Indexed: 01/25/2023] Open
Abstract
The aim of this study was to examine the association between tHbmass and HBB gene polymorphisms in athletes of endurance disciplines. Eighty-two well-trained athletes (female n=36, male n=46), aged 19.3 ± 2.7 years, representing cross country skiing (n=37) and middle- and long-distance running (n=45), participated in the study. Genotyping for 2 polymorphisms in the HBB gene (- 551C/T and intron 2, +16 C/G) was performed using restriction fragment length polymorphism analysis. Total haemoglobin mass (tHbmass) was determined by the optimized carbon monoxide rebreathing method. Blood morphology, indices of iron status (ferritin, transferrin receptor and total iron binding capacity) and C reactive protein were also determined. No differences were found in the HBB genotype and allele frequencies between male and female athletes. Regardless of the polymorphisms, no relationships were found between HBB genotypes as well as alleles and relative values of tHbmass, expressed per body mass (g · kg-1 BM), both in female and male athletes. Our results demonstrated that -551 C/T and intron 2, +16 C/G polymorphisms of the HBB gene have no association with total haemoglobin mass in endurance athletes. It cannot be ruled out that several polymorphisms, each with a small but significant contribution, may be responsible for the amount of haemoglobin.
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Rapid and inexpensive detection of common HBB gene mutations in Tunisian population by high-resolution melting analysis: implication for molecular diagnosis. ACTA ACUST UNITED AC 2013; 19:80-4. [PMID: 23683733 DOI: 10.1179/1607845413y.0000000096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In Tunisia, β-thalassemia is a common hereditary disease with a carrying rate of 2.21%. Up to now, detection of responsible mutations was made by laborious, expensive, and/or time consuming methods. The aim of this study is to develop and validate a specific assay for detection of the two most frequent mutations in Tunisian population, the IVS-I-110 (G → A) and Cd39 (C → T) mutations. In this study, we optimize high resolution melting analysis (HRMA) conditions for these mutations, using control DNAs. Then, we evaluate the strength of this methodology by screening a cohort of patients with β-thalassemia. All examined reference DNA samples were unambiguously distinguished from each other. For the blinded test, the results were completely compatible with direct sequencing, performed after the HRMA. As HRMA represents a highly sensitive and high-throughput gene scanning method, it can provide timely diagnosis at low cost for effective clinical management of β-thalassemia.
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