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Singha K, Srivorakun H, Fucharoen G, Fucharoen S. Molecular basis of Hb H and AEBart’s diseases in the Lao People’s Democratic Republic. Int J Lab Hematol 2019; 42:23-27. [DOI: 10.1111/ijlh.13118] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/04/2019] [Accepted: 10/12/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Kritsada Singha
- Centre for Research and Development of Medical Diagnostic Laboratories Faculty of Associated Medical Sciences Khon Kaen University Khon Kaen Thailand
| | - Hataichanok Srivorakun
- Centre for Research and Development of Medical Diagnostic Laboratories Faculty of Associated Medical Sciences Khon Kaen University Khon Kaen Thailand
| | - Goonnapa Fucharoen
- Centre for Research and Development of Medical Diagnostic Laboratories Faculty of Associated Medical Sciences Khon Kaen University Khon Kaen Thailand
| | - Supan Fucharoen
- Centre for Research and Development of Medical Diagnostic Laboratories Faculty of Associated Medical Sciences Khon Kaen University Khon Kaen Thailand
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2
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A cytosine-rich splice regulatory determinant enforces functional processing of the human α-globin gene transcript. Blood 2019; 133:2338-2347. [PMID: 30833414 DOI: 10.1182/blood-2018-12-891408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/26/2019] [Indexed: 01/28/2023] Open
Abstract
The establishment of efficient and stable splicing patterns in terminally differentiated cells is critical to maintenance of specific functions throughout the lifespan of an organism. The human α-globin (hα-globin) gene contains 3 exons separated by 2 short introns. Naturally occurring α-thalassemia mutations that trigger aberrant splicing have revealed the presence of cryptic splice sites within the hα-globin gene transcript. How cognate (functional) splice sites are selectively used in lieu of these cryptic sites has remained unexplored. Here we demonstrate that the preferential selection of a cognate splice donor essential to functional splicing of the hα-globin transcript is dependent on the actions of an intronic cytosine (C)-rich splice regulatory determinant and its interacting polyC-binding proteins. Inactivation of this determinant by mutation of the C-rich element or by depletion of polyC-binding proteins triggers a dramatic shift in splice donor activity to an upstream, out-of-frame, cryptic donor. The essential role of the C-rich element in hα-globin gene expression is supported by its coevolution with the cryptic donor site in primate species. These data lead us to conclude that an intronic C-rich determinant enforces functional splicing of the hα-globin transcript, thus acting as an obligate determinant of hα-globin gene expression.
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3
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Zhang H, Li C, Li J, Hou S, Chen D, Yan H, Chen S, Liu S, Yin Z, Yang X, Tan J, Huang X, Zhang L, Fang J, Zhang C, Li W, Guo J, Lei D. Next-generation sequencing improves molecular epidemiological characterization of thalassemia in Chenzhou Region, P.R. China. J Clin Lab Anal 2019; 33:e22845. [PMID: 30809867 PMCID: PMC6528559 DOI: 10.1002/jcla.22845] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/19/2018] [Accepted: 01/03/2019] [Indexed: 12/23/2022] Open
Abstract
Objectives Thalassemia is a highly prevalent monogenic inherited disease in southern China. It is important to collect epidemiological data comprehensively for proper prevention and treatment. Methods In this study, blood samples collected from 15 807 residents of Chenzhou were primarily screened by hematological tests. A total of 3973 samples of suspected thalassemia carriers were further characterized by combined next‐generation sequencing (NGS) and Gap‐PCR. Results In total, 1704 subjects were diagnosed as thalassemia carriers with a total prevalence rate of 10.78%, including 943 α‐thalassemia carriers, 708 β‐thalassemia carriers, and 53 composite α and β‐thalassemia carriers. The prevalence rates of α‐thalassemia, β‐thalassemia, and composite α and β‐thalassemia were 5.97%, 4.48%, and 0.34%, respectively. Meanwhile, we characterized 19 α‐thalassemia variations and 21 β‐thalassemia variations in thalassemia carriers. Approximately 2.88% of thalassemia carriers would be missed by traditional genetic analysis. In addition, four novel thalassemia mutations and one novel abnormal hemoglobin mutation were identified. Conclusions Our data suggest a high prevalence of thalassemia and a diverse spectrum of thalassemia‐associated variations in Chenzhou. Also, combined NGS and Gap‐PCR is an effective thalassemia screening method. Our findings might be helpful for prevention and treatment of thalassemia in this region.
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Affiliation(s)
- Haoqing Zhang
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
| | - Caiyun Li
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
| | - Jianbiao Li
- BGI-Shenzhen, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Shuai Hou
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
| | - Danjing Chen
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
| | - Haiying Yan
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
| | - Shiping Chen
- BGI Genomics, BGI-Shenzhen, Shenzhen, China.,Clinical Laboratory of BGI Health, BGI-Shenzhen, Shenzhen, China
| | - Saijun Liu
- BGI Genomics, BGI-Shenzhen, Shenzhen, China
| | - Zhenzhen Yin
- BGI-Shenzhen, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Xiaoqin Yang
- BGI Genomics, BGI-Shenzhen, Shenzhen, China.,Clinical Laboratory of BGI Health, BGI-Shenzhen, Shenzhen, China
| | - Jufang Tan
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
| | - Xiaoyan Huang
- BGI Genomics, BGI-Shenzhen, Shenzhen, China.,Clinical Laboratory of BGI Health, BGI-Shenzhen, Shenzhen, China
| | - Liming Zhang
- BGI Genomics, BGI-Shenzhen, Shenzhen, China.,Clinical Laboratory of BGI Health, BGI-Shenzhen, Shenzhen, China
| | - Junbin Fang
- BGI Genomics, BGI-Shenzhen, Shenzhen, China.,Clinical Laboratory of BGI Health, BGI-Shenzhen, Shenzhen, China
| | - Caifen Zhang
- BGI Genomics, BGI-Shenzhen, Shenzhen, China.,Clinical Laboratory of BGI Health, BGI-Shenzhen, Shenzhen, China
| | - Wei Li
- BGI Genomics, BGI-Shenzhen, Shenzhen, China
| | - Jian Guo
- BGI-Shenzhen, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Dongzhu Lei
- Center of Prenatal Diagnosis, Chenzhou No. 1 People's Hospital, Chenzhou, China
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4
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Alauddin H, Kamarudin K, Loong TY, Azma RZ, Ithnin A, Jalil N, Razak NF, Koh-Xuan-Rong D, Ismail E, C-Khai L, Abdul Latiff Z, Alias H, Othman A. A Unique Interaction of IVS-I-1 (G>A) (HBA2: c.95+1G>A) with Hb Adana (HBA2: c.179G>A) Presenting as Transfusion-Dependent α-Thalassemia. Hemoglobin 2019; 42:247-251. [PMID: 30623696 DOI: 10.1080/03630269.2018.1528985] [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: 10/27/2022]
Abstract
Nondeletional α-globin mutations are known to cause more serious clinical effects than deletional ones. A rare IVS-I-1 (G>A) (HBA2: c.95+1G>A) donor splice site mutation interferes with normal splicing of pre mRNA and results in activation of a cryptic splice site as well as a frameshift mutation. Hb Adana [HBA2: c.179G>A (or HBA1)] is a highly unstable variant hemoglobin (Hb) resulting from a mutation at codon 59 on the HBA2 or HBA1 gene, recognized to cause severe α-thalassemia (α-thal) syndromes. We report a unique case of compound heterozygosity for these two mutations in a 9-year-old boy who presented with a Hb level of 5.3 g/dL and hepatomegaly at the age of 15 months. He required regular blood transfusions in view of a Hb level of <7.0 g/dL and failure to thrive. He had thalassemic red cell indices and peripheral blood film. The Hb electrophoresis only showed a raised Hb F level (3.3%) and a pre run peak but the Hb H inclusion test was negative. His father had thalassemic red cell indices but a normal Hb level. His mother had almost normal Hb levels and red cell indices. Hb Adana involving the HBA2 gene was detected by mutiplex amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) in the proband and his father. DNA sequencing of the HBA2 gene confirmed the IVS-I-1 mutation in the proband and his mother. This case highlighted the unique interaction of the IVS-I-1 mutation with Hb Adana in a young Malay boy presenting with transfusion-dependent α-thal.
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Affiliation(s)
- Hafiza Alauddin
- a Department of Pathology , Universiti Kebangsaan Malaysia Medical Centre , Kuala Lumpur , Malaysia
| | - Khairina Kamarudin
- a Department of Pathology , Universiti Kebangsaan Malaysia Medical Centre , Kuala Lumpur , Malaysia
| | - Tang Yee Loong
- a Department of Pathology , Universiti Kebangsaan Malaysia Medical Centre , Kuala Lumpur , Malaysia
| | - Raja Zahratul Azma
- a Department of Pathology , Universiti Kebangsaan Malaysia Medical Centre , Kuala Lumpur , Malaysia
| | - Azlin Ithnin
- a Department of Pathology , Universiti Kebangsaan Malaysia Medical Centre , Kuala Lumpur , Malaysia
| | - Norunaluwar Jalil
- b Department of Laboratory Diagnostic Services , Universiti Kebangsaan Malaysia Medical Centre , Kuala , Lumpur , Malaysia
| | - Noor-Farisah Razak
- b Department of Laboratory Diagnostic Services , Universiti Kebangsaan Malaysia Medical Centre , Kuala , Lumpur , Malaysia
| | - Danny Koh-Xuan-Rong
- c School of Bioscience and Biotechnology , Universiti Kebangsaan Malaysia , Selangor , Malaysia
| | - Endom Ismail
- c School of Bioscience and Biotechnology , Universiti Kebangsaan Malaysia , Selangor , Malaysia
| | - Loh C-Khai
- d Department of Paediatrics , Universiti Kebangsaan Malaysia Medical Centre , Kuala , Lumpur , Malaysia
| | - Zarina Abdul Latiff
- d Department of Paediatrics , Universiti Kebangsaan Malaysia Medical Centre , Kuala , Lumpur , Malaysia
| | - Hamidah Alias
- d Department of Paediatrics , Universiti Kebangsaan Malaysia Medical Centre , Kuala , Lumpur , Malaysia
| | - Ainoon Othman
- e Department of Medical Science II , Faculty of Medicine and Health Science, Universiti Sains Islam Malaysia , Nilai , Malaysia
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5
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Farashi S, Najmabadi H. Diagnostic pitfalls of less well recognized HbH disease. Blood Cells Mol Dis 2015; 55:387-95. [DOI: 10.1016/j.bcmd.2015.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/06/2015] [Accepted: 08/06/2015] [Indexed: 10/23/2022]
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6
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Farashi S, Vakili S, Garous NF, Ashki M, Forouzesh Pour F, Zeinali F, Rad F, Imanian H, Azarkeivan A, Najmabadi H. Identification of Mutations Causing Aberrant Termination and Deficient Splice Donor Site on theHBA1Gene. Hemoglobin 2015; 40:38-43. [DOI: 10.3109/03630269.2015.1088456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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7
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Farashi S, Vakili S, Garous NF, Ashki M, Imanian H, Azarkeivan A, Najmabadi H. Mutations on theα2-Globin Gene That May Triggerα+-Thalassemia. Hemoglobin 2015; 39:398-402. [DOI: 10.3109/03630269.2015.1075890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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8
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Suresh S, Fisher C, Ayyub H, Premawardhena A, Allen A, Perera A, Bandara D, Olivieri N, Weatherall D. Alpha thalassaemia and extended alpha globin genes in Sri Lanka. Blood Cells Mol Dis 2012; 50:93-8. [PMID: 23138098 DOI: 10.1016/j.bcmd.2012.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 10/08/2012] [Indexed: 11/30/2022]
Abstract
The α-globin genes were studied in nine families with unexplained hypochromic anaemia and in 167 patients with HbE β thalassaemia in Sri Lanka. As well as the common deletion forms of α(+) thalassaemia three families from an ethnic minority were found to carry a novel form of α(0) thalassaemia, one family carried a previously reported form of α(0) thalassaemia, --(THAI), and five families had different forms of non-deletional thalassaemia. The patients with HbE β thalassaemia who had co-inherited α thalassaemia all showed an extremely mild phenotype and reduced levels of HbF and there was a highly significant paucity of α(+) thalassaemia in these patients compared with the normal population. Extended α gene arrangements, including ααα, αααα and ααααα, occurred at a low frequency and were commoner in the more severe phenotypes of HbE β thalassaemia. As well as emphasising the ameliorating effect of α thalassaemia on HbE β thalassaemia the finding of a novel form of α(0) thalassaemia in an ethnic minority, together with an unexpected diversity of forms of non-deletion α thalassaemia in Sri Lanka, further emphasises the critical importance of micro-mapping populations for determining the frequency of clinically important forms of the disease.
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Scheps KG, Binaghi A, Varela V. Identification of a New HBA1 Gene Mutation (HBA1:c.301-2A>T) inCiswith Hb Riccarton (HBA1:c.154G>A) [α51(CE9)Gly→Ser]. Hemoglobin 2012; 36:504-7. [DOI: 10.3109/03630269.2012.700897] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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10
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11
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Qadah T, Finlayson J, Ghassemifar R. In vitroCharacterization of the α-Thalassemia Point Mutation HBA2:c.95+1G>A [IVS-I-1(G>A) (α2)]. Hemoglobin 2011; 36:38-46. [DOI: 10.3109/03630269.2011.599086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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12
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Harteveld CL, Wijermans PW, van Delft P, Rasp E, Haak HL, Giordano PC. An α‐Thalassemia Phenotype in a Dutch Hindustani, Caused by a New Point Mutation that Creates an Alternative Splice Donor Site in the First Exon of the α2‐Globin Gene. Hemoglobin 2009; 28:255-9. [PMID: 15481895 DOI: 10.1081/hem-120040257] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The proband is an elderly woman (79 years of age) of Surinamese-Hindustani origin, suspected of being a carrier of a nondeletional alpha-thalassemia (thal) because of a moderate microcytic hypochromic anemia at normal ferritin levels and in the absence of any other alpha-thal deletions. Sequence analysis revealed a silent mutation (GGC-->GGT) at codon 22 of the alpha2-globin gene. This mutation generates a splice donor site consensus sequence (GGTGAG) between codons 22 and 23. The abnormally spliced mRNA leads to a premature termination between codons 48 and 49. The presence of a downstream intron may induce the intracellular degradation of the affected mRNA, a pathway known as nonsense mediated decay (NMD), and this explains the alpha(+)-thal phenotype observed in the patient. The codon 22 (GGC-->GGT) transition described in this report is the first mutation creating a splice donor site in one of the alpha-globin genes.
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Affiliation(s)
- Cornelis L Harteveld
- Hemoglobinopathies Laboratory, Department of Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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13
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Harteveld CL, Yavarian M, Zorai A, Quakkelaar ED, van Delft P, Giordano PC. Molecular spectrum of alpha-thalassemia in the Iranian population of Hormozgan: three novel point mutation defects. Am J Hematol 2003; 74:99-103. [PMID: 14508795 DOI: 10.1002/ajh.10385] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We describe the molecular spectrum of alpha-thalassemia mutations in a population sample of newborns in the South-Iranian province of Hormozgan. Out of 660 randomly collected blood samples 218 (33%) had visibly elevated Hb Bart's. DNA was extracted from 78 samples out of this selection (n=156), of which 114 alleles were found to carry an alpha-thalassemia defect. Besides the common -alpha3.7 (79.1%), -alpha4.2 (1.7%), and alpha-5nt alpha alleles (4.3%), three novel nondeletional alpha-thalassemia mutations were found; the alpha2 cd19 (-G) frameshift mutation (12.2%), the alpha1 IVS1-148(A-->G) (0.9%) affecting the splice acceptor site consensus sequence and the cd14 (TGG-->TAG) (0.9%), which creates a premature stop codon in the first exon of the alpha1-gene. A fourth mutation in the alpha1-gene, the IVS1-38 (C-->T) (0.9%) of undetermined effect, was found in an individual heterozygous for the alpha2 cd19(-G) mutation.
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Affiliation(s)
- C L Harteveld
- Hemoglobinopathies Laboratory, Human and Clinical Genetics, Leiden University Medical Centre, The Netherlands.
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14
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Harteveld CL, Beijer C, van Delft P, Zanardini R, Bernini LF, Giordano PC. alpha-thalassaemia as a result of a novel splice donor site mutation of the alpha1-globin gene. Br J Haematol 2000; 110:694-8. [PMID: 10997982 DOI: 10.1046/j.1365-2141.2000.02225.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We describe the characterization of an alpha+-thalassaemia determinant as a result of a transition of G-->A of the donor splice consensus site sequence of the first intron of the alpha1-globin gene (alpha1IVS I-1). The mutation was found in combination with the South-East Asian alpha0-thalassaemia deletion in an haemoglobin (Hb)H patient and her sister, both of Thai origin. Sequencing of the abnormally spliced mRNA product revealed the presence of a cryptic splice site in exon 1 of the alpha1-globin gene. No normally spliced alpha1mRNA was detected. The abnormally spliced mRNA product from the alpha1-gene carrying the mutation does not lead to functional protein and causes a mild HbH-disease phenotype when in combination with the deletion type alpha0-thalassaemia.
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Affiliation(s)
- C L Harteveld
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands.
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Abstract
alpha-Thalassaemias are genetic defects extremely frequent in some populations and are characterized by the decrease or complete suppression of alpha-globin polypeptide chains. The gene cluster, which codes for and controls the production of these polypeptides, maps near the telomere of the short arm of chromosome 16, within a G + C rich and early-replicating DNA region. The genes expressed during the embryonic (zeta) or fetal and adult stage (alpha 2 and alpha 1) can be modified by point mutations which affect either the processing-translation of mRNA or make the polypeptide chains extremely unstable. Much more frequent are the deletions of variable size (from approximately 3 to more than 100 kb) which remove one or both alpha genes in cis or even the whole gene cluster. Deletions of a single gene are the result of unequal pairing during meiosis, followed by reciprocal recombination. These unequal cross-overs, which produce also alpha gene triplications and quadruplications, are made possible by the high degree of homology of the two alpha genes and of their flanking sequences. Other deletions involving one or more genes are due to recombinations which have taken place within non-homologous regions (illegitimate recombinations) or in DNA segments whose homology is limited to very short sequences. Particularly interesting are the deletions which eliminate large DNA areas 5' of zeta or of both alpha genes. These deletions do not include the structural genes but, nevertheless, suppress completely their expression. Larger deletions involving the tip of the short arm of chromosome 16 by truncation, interstitial deletions or translocations result in the contiguous gene syndrome ATR-16. In this complex syndrome alpha-thalassaemia is accompanied by mental retardation and variable dismorphic features. The study of mutations of the 5' upstream flanking region has led to the discovery of a DNA sequence, localized 40 kb upstream of the zeta-globin gene, which controls the expression of the alpha genes (alpha major regulatory element or HS-40). In the acquired variant of haemoglobin H (HbH) disease found in rare individuals with myelodysplastic disorders and in the X-linked mental retardation associated with alpha-thalassaemia, a profound reduction or absence of alpha gene expression has been observed, which is not accompanied by structural alterations of the coding or controlling regions of the alpha gene complex. Most probably the acquired alpha-thalassaemia is due to the lack of soluble activators (or presence of repressors) which act in trans and affect the expression of the homologous clusters and are coded by genes not (closely) linked to the alpha genes. The ATR-X syndrome results from mutations of the XH2 gene, located on the X chromosome (Xq13.3) and coding for a transacting factor which regulates gene expression. The interaction of the different alpha-thalassaemia determinants results in three phenotypes: the alpha-thalassaemic trait, clinically silent and presenting only limited alterations of haematological parameters, HbH disease, characterized by the development of a haemolytic anaemia of variable degree, and the (lethal) Hb Bart's hydrops fetalis syndrome. The diagnosis of alpha-thalassaemia due to deletions is implemented by the electrophoretic analysis of genomic DNA digested with restriction enzymes and hybridized with specific molecular probes. Recently polymerase chain reaction (PCR) based strategies have replaced the Southern blotting methodology. The straightforward identification of point mutations is carried out by the specific amplification of the alpha 2 or alpha 1 gene by PCR followed by the localization and identification of the mutation with a variety of screening systems (denaturing gradient gel electrophoresis (DGGE), single strand conformation polymorphisms (SSCP)) and direct sequencing.
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Affiliation(s)
- L F Bernini
- Institute of Human Genetics, Medical Faculty, University of Leiden, Sylvius Laboratory, The Netherlands
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Kattamis AC, Camaschella C, Sivera P, Surrey S, Fortina P. Human alpha-thalassemia syndromes: detection of molecular defects. Am J Hematol 1996; 53:81-91. [PMID: 8892732 DOI: 10.1002/(sici)1096-8652(199610)53:2<81::aid-ajh5>3.0.co;2-#] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- A C Kattamis
- Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine 19104, USA
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18
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Ayala S, Colomer D, Aymerich M, Pujades A, Vives-Corrons JL. Nondeletional alpha-thalassemia: first description of alpha Hph alpha and alpha Nco alpha mutations in a Spanish population. Am J Hematol 1996; 52:144-9. [PMID: 8756078 DOI: 10.1002/(sici)1096-8652(199607)52:3<144::aid-ajh3>3.0.co;2-t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Several different deletions underlie the molecular basis of alpha-thalassemia. The most common alpha-thalassemia determinant in Spain is the rightward deletion (-alpha 3.7). To our knowledge, however, no cases of alpha-thalassemia due to nondeletional mutations have so far been described in this particular Mediterranean area. Here, we report the existence of nondeletional forms of alpha-thalassemia in ten Spanish families. The alpha 2-globin gene was characterized in ten unrelated patients and their relatives only when the presence of deletional alpha-thalassemia was ruled out. The alpha 2-globin gene analysis was performed using the polymerase chain reaction (PCR) followed by restriction enzyme analysis or by allelespecific priming. This allowed the identification of a 5-base pair (bp) deletion at the donor site of IVS I (alpha Hph alpha) in 9 cases and the alpha 2 initiation codon mutation (alpha Nco alpha) in one case. Although these alpha 2-globin gene mutations are found in other mediterranean areas, our results demonstrate their presence in the Spanish population and suggest that the alpha Hph alpha/alpha alpha genotype is probably the most common nondeletional form of alpha-thalassemia in Spain.
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Affiliation(s)
- S Ayala
- Hematology Laboratory Department, Hospital Clínic i Provincial, Postgraduate School of Hematology Farreras Valentí, University of Barcelona, Catalonia, Spain
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Mach-Pascual S, Darbellay R, Pilotto PA, Beris P. Investigation of microcytosis: a comprehensive approach. Eur J Haematol 1996; 57:54-61. [PMID: 8698132 DOI: 10.1111/j.1600-0609.1996.tb00490.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Microcytosis is a highly prevalent finding during blood examination. This study investigates the causes of microcytosis (defined as mean corpuscular volume (MCV) < 82 fl) in 466 patients referred to our laboratory for suspected hemoglobinopathy. The following data were obtained: Hb, MCV, serum iron, transferrin, ferritin, HbA2, HbF, isoelectric focusing of the Hb, gene mapping of chromosome 16 with Xba I and Bgl II and hybridization with an alpha- and a zeta-probe, inflammatory status. Results show that iron deficiency remains the first cause of microcytosis (35.2% of our patients), even in a selected population such as ours. Deletional alpha-thalassemia, probably the most frequent hemoglobinopathy throughout the world, represents the second most frequent cause of microcytosis (31.1%), followed by beta-thalassemia heterozygous state (18.9%). Of our patients, 1.3% had microcytosis due to the presence of an abnormal hemoglobin (HbC, Hb S/C, HbE). Three cases (0.6%) had other possible causes of microcytosis. Of the remaining 60 cases, 28 had an inflammatory state. Finally, 32 cases (6.9%) remain unexplained; taking into consideration the origin of these cases, their hematological parameters and their family history, we postulate that these cases are at high risk for non-deletional alpha-thalassemia.
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Affiliation(s)
- S Mach-Pascual
- Division of Hematology, University Hospital, Geneva, Switzerland
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Abstract
Sickle cell anemia is noted for being phenotypically heterogeneous. This suggests that there are genetic influences that moderate the effects of the sickle hemoglobin mutation. In this review I focus on genetically determined modulation of hemoglobin concentration and fetal hemoglobin levels. Each of these variables has important influences upon sickle hemoglobin polymerization and the resulting pathophysiology.
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Affiliation(s)
- M H Steinberg
- Department of Medicine, University of Mississippi School of Medicine, Jackson 39216, USA
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Darbellay R, Mach-Pascual S, Rose K, Graf J, Beris P. Haemoglobin Tunis-Bizerte: a new alpha 1 globin 129 Leu-->Pro unstable variant with thalassaemic phenotype. Br J Haematol 1995; 90:71-6. [PMID: 7786798 DOI: 10.1111/j.1365-2141.1995.tb03382.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A Leu-->Pro substitution at position 129 of the alpha 1 globin gene was detected in three members of a Tunisian family by sequencing the whole alpha 2 and alpha 1 DNA. The mutation was verified by dot-blot allele-specific hybridization as well as by digestion of PCR and RT-PCR products with Nci I, since the alpha 1(129) T-->C mutation creates an additional recognition site for the above-mentioned enzyme. The alpha 1(129)(H12)Leu-->Pro substitution disturbs helix H resulting in alpha-thal trait most probably because the unstable alpha-globin chain variant cannot form alpha beta dimers. A search for the abnormal Hb and for the abnormal alpha globin chain by isoelectric focusing, carboxymethyl cellulose chromatography and electrospray ionization mass spectrometry was negative. In the heterozygous state, the alpha 1(129)(H12) Leu-->Pro variant is manifested by microcytosis (MCV approximately 73 fl), whereas in the homozygous state there is moderate anaemia with marked microcytosis (Hb 11.6 g/dl, MCV 65 fl).
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Affiliation(s)
- R Darbellay
- Division of Haematology, Hôpital Cantonal Universitaire de Genève, Switzerland
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Molchanova TP, Pobedimskaya DD, Huisman TH. The differences in quantities of alpha 2- and alpha 1-globin gene variants in heterozygotes. Br J Haematol 1994; 88:300-6. [PMID: 7803274 DOI: 10.1111/j.1365-2141.1994.tb05022.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have identified through sequencing of amplified DNA the mutations in the alpha 2- and alpha 1-globin genes in 63 individuals with a heterozygosity for an alpha chain abnormal haemoglobin (Hb). Moreover, we developed a reverse transcription/polymerase chain reaction (RT/PCR) based procedure for the determination of the alpha 2- and alpha 1-mRNA ratio in normal individuals. The numbers of alpha 2 and alpha 1 variants were nearly the same. The average percentage of the abnormal Hb in heterozygotes with alpha 2 mutations (23.5%) was slightly higher than that in heterozygotes with alpha 1 mutations (19.7%) (stable Hbs only). These percentages correspond to a ratio of alpha 2 to alpha 1 of 1.19 to 1 at the protein level. Variations in the number of active alpha-globin genes and in the stability of the variants (greatly) affected the percentages of the abnormal protein. The average ratio between the alpha 2- and alpha 1-mRNAs in 12 normal individuals was 2.6-2.75 to 1, about as expected from published data, and 2.0 to 1 for two persons with an alpha-thalassaemia-2 (alpha-thal-2) (-3.7 kb) heterozygosity. The high relative mRNA (alpha 2) level which is about twice the relative level of the alpha 2 protein suggests a less efficient translation of the alpha 2-mRNA.
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Affiliation(s)
- T P Molchanova
- Laboratory of Protein Chemistry, Medical College of Georgia, Augusta 30912-2100
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