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Mahmud N, Maffei M, Mogni M, Forni GL, Pinto VM, Barberio G, Ungari S, Maffè A, Curcio C, Zanolli F, Paventa R, Carta M, Caleffi A, Mercadanti M, Maoggi S, Ivaldi G, Coviello D. Hemoglobin A 2 and Heterogeneous Diagnostic Relevance Observed in Eight New Variants of the Delta Globin Gene. Genes (Basel) 2021; 12:genes12111821. [PMID: 34828427 PMCID: PMC8625798 DOI: 10.3390/genes12111821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/15/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Hemoglobin A (Hb A) (α2β2) in the normal adult subject constitutes 96-98% of hemoglobin, and Hb F is normally less than 1%, while for hemoglobin A2 (Hb A2) (α2δ2), the normal reference values are between 2.0 and 3.3%. It is important to evaluate the presence of possible delta gene mutations in a population at high risk for globin gene defects in order to correctly diagnose the β-thalassemia carrier. METHODS The most used methods for the quantification of Hb A2 are based on automated high performance liquid chromatography (HPLC) or capillary electrophoresis (CE). In particular Hb analyses were performed by HPLC on three dedicated devices. DNA analyses were performed according to local standard protocols. RESULTS Here, we described eight new δ-globin gene variants discovered and characterized in some laboratories in Northern Italy in recent years. These new variants were added to the many already known Hb A2 variants that were found with an estimated frequency of about 1-2% during the screening tests in our laboratories. CONCLUSIONS The knowledge recognition of the delta variant on Hb analysis and accurate molecular characterization is crucial to provide an accurate definitive thalassemia diagnosis, particularly in young subjects who would like to ask for a prenatal diagnosis or preimplantation genetic diagnosis.
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Affiliation(s)
- Noraesah Mahmud
- Laboratorio Genetica Umana, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy; (N.M.); (M.M.); (D.C.)
- Department of Pathology, Hospital Kuala Lumpur, Kuala Lumpur 50586, Malaysia
| | - Massimo Maffei
- Laboratorio Genetica Umana, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy; (N.M.); (M.M.); (D.C.)
- Correspondence:
| | - Massimo Mogni
- Laboratorio Genetica Umana, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy; (N.M.); (M.M.); (D.C.)
| | - Gian Luca Forni
- Centro Microcitemia e Anemie Congenite, Ospedali Galliera, 16128 Genova, Italy; (G.L.F.); (V.M.P.)
| | - Valeria Maria Pinto
- Centro Microcitemia e Anemie Congenite, Ospedali Galliera, 16128 Genova, Italy; (G.L.F.); (V.M.P.)
| | - Giuseppina Barberio
- Medicina di Laboratorio, Azienda ULSS 2 Marca Trevigiana, 31100 Treviso, Italy;
| | - Silvana Ungari
- Genetica e Biologia Molecolare ASO S. Croce e Carle, 12100 Cuneo, Italy; (S.U.); (A.M.)
| | - Antonella Maffè
- Genetica e Biologia Molecolare ASO S. Croce e Carle, 12100 Cuneo, Italy; (S.U.); (A.M.)
| | - Cristina Curcio
- Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milano, Italy;
| | - Francesco Zanolli
- Formerly, Servizio di Immunoematologia e Medicina Trasfusionale, A.O. Santa Maria degli Angeli, 33170 Pordenone, Italy;
| | | | - Mariarosa Carta
- Medicina di Laboratorio, Ospedale S. Bortolo, AULSS 8 Berica, 36100 Vicenza, Italy;
| | - Alberta Caleffi
- U.O. Diagnostica Ematochimica, Azienda Ospedaliero-Universitaria, 43126 Parma, Italy; (A.C.); (M.M.)
| | - Mariella Mercadanti
- U.O. Diagnostica Ematochimica, Azienda Ospedaliero-Universitaria, 43126 Parma, Italy; (A.C.); (M.M.)
| | - Sauro Maoggi
- Sebia-Italia S.r.l., 50012 Bagno a Ripoli, Italy;
| | - Giovanni Ivaldi
- Formerly, Laboratorio Genetica Umana, Galliera Hospital, 16128 Genova, Italy;
| | - Domenico Coviello
- Laboratorio Genetica Umana, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy; (N.M.); (M.M.); (D.C.)
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Colaco S, Nadkarni A. Borderline HbA 2 levels: Dilemma in diagnosis of beta-thalassemia carriers. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108387. [PMID: 34893152 DOI: 10.1016/j.mrrev.2021.108387] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 05/27/2021] [Accepted: 06/08/2021] [Indexed: 12/17/2022]
Abstract
There is inconsistency in the exact definition of diagnostic levels of HbA2 for β thalassemia trait. While many laboratories consider HbA2 ≥4.0 % diagnostic, still others consider HbA2 ≥3.3 % or HbA2 ≥3.5 % as the cut-off for establishing β thalassemia carrier diagnosis. This is because, over the years, studies have described β thalassemia carriers showing HbA2 levels that lie above the normal range of HbA2 but below the typical carrier range of β thalassemia. These, "borderline HbA2 levels", though not detrimental to health, are significant in β thalassemia carrier diagnosis because they can lead to misinterpretation of results. In this review, we have evaluated the prevalence of borderline HbA2 levels and discussed the causes of borderline HbA2 values. We have also compiled an extensive catalogue of β globin gene defects associated with borderline HbA2 levels and have discussed strategies to avoid misdiagnosing borderline HbA2 β thalassemia carriers. Our analysis of studies that have delineated the cause of borderline HbA2 levels in different populations shows that 35.4 % [626/1766] of all individuals with borderline HbA2 levels carry a molecular defect. Among the positive samples, 17 % [299/1766] show β globin gene defects, 7.7 % [137/1766] show α thalassemia defects, 2.7 % [49/1766] show KLF1 gene mutations, 2.3 % [41/1766] show the co-inheritance of β and α thalassemia, 2.0 % [37/1766] show the co-inheritance of β and δ thalassemia and 1.8 % [32/1766] show α globin gene triplication. It appears that a comprehensive molecular work up of the β globin gene is the only definite method to detect borderline HbA2 β thalassemia carriers, especially in populations with a high prevalence of the disease. The presence of associated genetic or acquired determinants may subsequently be assessed to identify the cause of borderline HbA2.
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Affiliation(s)
- Stacy Colaco
- Department of Hematogenetics, ICMR-National Institute of Immunohematology, 13th Floor, K.E.M. Hospital Campus, Parel, Mumbai, 400 012, India
| | - Anita Nadkarni
- Department of Hematogenetics, ICMR-National Institute of Immunohematology, 13th Floor, K.E.M. Hospital Campus, Parel, Mumbai, 400 012, India.
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3
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Hb Knossos (HBB: c.82G > T), β-globin CD 5 (-CT) (HBB: c.17_18delCT) and δ-globin CD 59 (-a) (HBD: c.179delA) mutations in a Syrian patient with β-thalassemia intermedia. BMC Pediatr 2019; 19:61. [PMID: 30777047 PMCID: PMC6378710 DOI: 10.1186/s12887-019-1435-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 02/12/2019] [Indexed: 12/18/2022] Open
Abstract
Background Beta thalassemia (β-thal) is an inherited hemoglobin disorder characterized by reduced synthesis of the hemoglobin that results in microcytic hypochromic anemia. β-Thalassemia intermedia (TI) is a clinical term of intermediate gravity between the carrier state and β-thalassemia major (β -TM). Case presentation We describe a 12-year-old male proband originating from Al-Quneitra province - southwest Syria. Hematological investigations revealed, pallor and anemia (Hb 9 g/dl). The mean cell volume (MCV) 64 fL; mean cell hemoglobin (MCH) 21.8 pg. Capillary electrophoresis (CE) electropherogram revealed low level of Hb A1 (36.2%), high level of Hb F (62.2%) and low level of Hb A2 (1.6%). The proband requires blood transfusion occasionally. Direct DNA sequencing and Polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) for mutations detection were used. The molecular analysis revealed the presence of rare β+ Hb Knossos codon 27 (G > T) (HBB: c.82G > T) variant associated with β0 codon 5 [−CT] (HBB: c.17_18delCT) mutation in beta-globin (β-globin) gene and δ0 codon 59 [−A] (HBD: c.179delA) mutation in delta-globin (δ-globin) gene. The proband tested negative for the common deletional forms of alpha thalassemia (α-thal). Polymorphism of the Xmn-I locus (HBG2: c.-211C > T) revealed that the proband had a homozygous [TT] for Xmn-1 locus. Conclusions To our knowledge, this is the first report of beta thalassemia intermedia due to combination of Hb Knossos /codon 5 [−CT] associated with δ0 codon 59 [−A] in Syrian patient. On the other hand, in Syria, β-thal carriers who have low level of Hb A2 due to decreased δ-chain production, different δ-thal gene mutations must be screened to avoid the failure diagnosis of β-thal disease.
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González Borrachero ML, de la Fuente-Gonzalo F, González FA, Nieto JM, Villegas A, Ropero P. [Delta⁰-thalassemia by insertion of 27 base pairs in δ-globin gene with decreased hemoglobin A₂ levels]. Med Clin (Barc) 2015; 144:312-6. [PMID: 25579773 DOI: 10.1016/j.medcli.2014.10.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/16/2014] [Accepted: 10/23/2014] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND OBJECTIVE We describe a novel delta-thalassemia mutation causing decreased hemoglobin (Hb) A2 levels associated with Hb Watts, variant Hb resulting from a trinucleotide deletion in Spain. PATIENTS AND METHOD Hb variant analysis was performed by cation-exchange high performance liquid chromatography (HPLC) and capillary zone electrophoresis. Polymerase chain reaction and DNA sequence analyses were used to identify mutations in the δ- and α-globin genes. RESULTS Abnormal Hb was observed on capillary zone electrophoresis in Z6 and by cation-exchange HPLC a slower peak than HbA was observed at an retention time of 4.19min. This variant Hb is called Hb Watts [α2 74(EF3)Asp->0 or α2 75(EF4)Asp->0; HBA2:c.226_228delGAC]. The decreased HbA2 percentage owes to an insertion of 27nt between nt 83 and 84 of IVS-I of the δ-globin gene. CONCLUSIONS When analyzing a chromatogram, the possibility of the existence of delta-thalassemia or an HbA2 variant should be considered, apart from alfa-, beta-thalassemia and structural haemoglobinopathies. To this end, each of the peaks and their percentages should be considered to allow for correct interpretation and to avoid misdiagnosis as much as possible.
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Affiliation(s)
| | | | | | - Jorge M Nieto
- Servicio de Hematología y Hemoterapia, Hospital Clínico San Carlos, Madrid, España
| | - Ana Villegas
- Servicio de Hematología y Hemoterapia, Hospital Clínico San Carlos, Madrid, España
| | - Paloma Ropero
- Servicio de Hematología y Hemoterapia, Hospital Clínico San Carlos, Madrid, España.
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5
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Abstract
The β-thalassemias are characterized by a quantitative deficiency of β-globin chains underlaid by a striking heterogeneity of molecular defects. Although most of the molecular lesions involve the structural β gene directly, some down-regulate the gene through distal cis effects, and rare trans-acting mutations have also been identified. Most β-thalassemias are inherited in a Mendelian recessive fashion but there is a subgroup of β-thalassemia alleles that behave as dominant negatives. Unraveling the molecular basis of β-thalassemia has provided a paradigm for understanding of much of human genetics.
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Affiliation(s)
- Swee Lay Thein
- Department of Haematological Medicine, King's College London School of Medicine/King's College Hospital NHS Foundation Trust, London SE5 9NU, United Kingdom.
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7
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Pavlou E, Phylactides M, Kyrri A, Kalogerou E, Makariou C, Georgiou I, Kleanthous M. δ-Thalassemia in Cyprus. Hemoglobin 2009; 30:455-62. [PMID: 16987800 DOI: 10.1080/03630260600868006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
To help clarify the hematological picture of patients who may be positive for beta- and delta-globin gene mutations, the following study was carried out. Our aim was to identify the delta-globin gene mutations found in the Greek Cypriot population, their frequencies and the Hb A2 values associated with them. Seventy-four samples were selected from a random sample of 5,030 individuals, and the database of the Molecular Genetics Thalassaemia Department containing diagnostic analyses data was also mined for relevant information. Four novel for Cyprus delta-globin gene mutations: -30 (T-->C), Hb A2-Wrens [delta98(FG5)Val-->Met, GTG-->ATG], IVS-I-2 (T-->C) and Hb A2-Yokoshima [delta25(B7)Gly-->Asp (GGT-->GAT)] were identified. Hb A2-Yialousa [delta27(B9)Ala-->Ser, GCC-->TCC], Hb A2-Yokoshima, Hb A2-Troodos [delta116(G18)Arg-->Cys, CGC-->TGC], Hb A2-Pelendri [delta141(H19)Leu-->Pro, CTG-->CCG], codon 4 [delta4(A1)Thr-->Ile], codon 59 (-A), Hb A2-Wrens, IVS-II-897 (A-->G), IVS-I-2, -55 (T-->C) and -30 bring the total to 11 delta-globin alleles found in the Greek Cypriot population. Hb A2-Yialousa is the most common mutation followed by codon 4, with frequencies of 60.7 and 17.8%, respectively.Hb A2 levels above 1.9% have been found to indicate a significantly reduced possibility for the presence of a delta-globin gene mutation in this population. For Hb A2 levels of 1.7 and 1.8% the possibility of a delta-globin gene mutation rises to 90.9% and reaches 100% for lower Hb A2 levels. The frequency of all the mutant delta-globin chromosomes in the sample is 0.0067 and the carrier frequency is 1.26%.
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Affiliation(s)
- Eleni Pavlou
- Molecular Genetics Thalassaemia Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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8
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Moumni I, Zorai A, Daoued BB, Mosbahi I, Omar S, Kaabachi N, Dellagi K, Abbes S. Hb A2-Pasteur-Tunis [δ59(E3)Lys→Asn, AAG→AAC]: A New δ Chain Variant Detected by DNA Sequencing in a Tunisian Carrier of the Codon 39 (C→T) β0-Thalassemia Mutation. Hemoglobin 2009; 31:23-9. [PMID: 17365002 DOI: 10.1080/03630260601057005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We describe a new delta-globin variant, Hb A2-Pasteur-Tunis [delta59(E3)Lys-->Asn, AAG-->AAC]. This hemoglobin (Hb) displayed an electrophoretic mobility faster than normal Hb A2 and was expressed at 2.2 %. The molecular defect was characterized by DNA sequencing and confirmed by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-designed protocol. Hb A2-Pasteur-Tunis was found in a carrier of a codon 39 (C-->T) beta0-thalassemia (thal), presenting with a normal Hb A2 level. Phenotype and genotype investigations revealed that the total Hb A2 level of the patient was that expected for a minor beta-thal (4.8%).
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Affiliation(s)
- Imen Moumni
- Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur, Tunis, Tunisia
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9
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Keser I, Manguoglu E, Kayisli O, Yesilipek A, Luleci G. Combination of Hb Knossos [Cod 27 (G-T)] and IVSII-745 (C-G) in a Turkish patient with beta-thalassemia major. GENETIC TESTING 2007; 11:228-230. [PMID: 17949282 DOI: 10.1089/gte.2006.0521] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Beta-thalassemia is the most common disease among hemoglobinopathies in Antalya, Turkey, as well as world-wide. Mutations found in Turkish beta-thalassemia patients constitute a heterogeneous group, consisting mostly of point mutations. Only in very rare cases did deletions or insertions cause affected or carrier phenotypes. Hb Knossos [beta 27 (B9) Ala-Ser] is a rare variant with a normal HbA2 level. In this study, we aimed to investigate the effect of compound heterozygosity for Hb Knossos [Cod 27 (G-T)] and IVSII-745 (C-G). To our knowledge, this is the first report of such a combination related with beta-thalassemia major phenotype in a Turkish family, where reverse dot blot hybridization (RDBH) and DNA sequencing analysis were used. Heterozygous inheritance of the mutation results in mild beta-thalassemia phenotype, whereas homozygous inheritance leads to intermediate beta-thalassemia. As a result, the compound heterozygosity of Hb Knossos with IVSII-745 appears as the cause of the beta-thalassemia major phenotype in our case. The combination of these mutations [Hb Knossos, Cod 27 (G-T), and IVSII-745, C-G] causes the beta-thalassemia major phenotype, and this is important for genetic counseling.
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Affiliation(s)
- Ibrahim Keser
- Department of Medical Biology and Genetics, Medical School, Akdeniz University, 07070, Antalya, Turkey.
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10
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Abstract
This paper review the most important aspects of carrier detection procedures, genetic counselling, population screening and prenatal diagnosis of beta-thalassemias. Carrier detection can be made retrospectively, following the birth of an affected child or prospectively. Several programmes, with the aim of preventing homozygous beta-thalassemia, based on carrier screening and counselling of couples at marriage; preconception or early pregnancy, are operating in several Mediterranean at-risk populations. These programmes have been very effective, as indicated by increasing knowledge on thalassemia and its prevention by the target population and by the marked decline of the incidence of thalassemia major. Carrier detection is carried out by haematological methods followed by mutation detection by DNA analysis. Prenatal diagnosis is accomplished by mutation analysis on PCR-amplified DNA from chorionic villi. Future prospects include automation of the process of mutation-detection, simplification of preconception and preimplantation diagnosis and fetal diagnosis by analysis of fetal cells in maternal circulation.
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Affiliation(s)
- Antonio Cao
- Dipartimento di Scienze Biomediche e Biotecnologie, Università Studi Cagliari, Italy
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11
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Cao A, Rosatelli MC, Monni G, Galanello R. Screening for thalassemia: a model of success. Obstet Gynecol Clin North Am 2002; 29:305-28, vi-vii. [PMID: 12108831 DOI: 10.1016/s0889-8545(01)00006-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Programs of prospective carrier screening and genetic counseling for beta-thalassemia among couples planning marriage, preconception, or during early pregnancy are ongoing in several at-risk populations in the Mediterranean area, including Greeks, Greek Cypriots and Continental Italians. Carrier detection is carried out by haematological analysis followed by mutation detection by DNA analysis. Once carrier couples are identified, prenatal diagnosis is accomplished by mutation analysis on PCR amplified DNA from chorionic villi. These programs have been very effective, due to education programs and subsequent acceptance of screening. Future prospects include automation of the process of mutation detection by microchips analysis, introduction of preconception and preimplantation diagnosis and hopefully fetal diagnosis by analysis of fetal cells in maternal circulation.
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Affiliation(s)
- Antonio Cao
- Department of Pediatrics, Università degli Studi di Cagliari, Sardinia, Italy.
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12
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Oner R, Birben E, Acar C, Oner C, Kara A, Gümrük F, Gürgey A, Altay C. Molecular analysis of turkish beta-thalassemia heterozygotes with normal Hb A2 levels. Hemoglobin 2000; 24:195-201. [PMID: 10975439 DOI: 10.3109/03630260008997527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Four parents of three unrelated families who are obligatory beta-thalassemia heterozygotes and two parents with Hb Knossos are presented. In these subjects, although the red blood cell counts and red cell indices were compatible with beta-thalassemia trait, the Hb A2 values were between 1.9-2.9% of the total hemoglobin. Examination of the delta-globin gene by Southern blot, restriction endonuclease analysis, and by direct sequencing of amplified DNA revealed the presence of the (delta0) -7.2 kb Corfu type deletion, the (delta+) codon 27 (G-->T) and (delta0) IVS-I-2 (T-->C) mutations in trans or in cis with a severe beta-thalassemia allele, and the (delta0) codon 59 (-A) deletion in cis with the betaKnossos allele.
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Affiliation(s)
- R Oner
- Hacettepe University, Faculty of Science, Department of Biology, Beytepe, Ankara, Turkey.
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13
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Drakoulakou O, Papapanagiotou E, Loutradi-Anagnostou A, Papadakis M. delta-Thalassemic phenotype due to two "novel" delta-globin gene mutations: CD11[GTC-->GGC (A8)-HbA2-Pylos] and CD 85[TTT-->TCT(F1)-HbA2-Etolia]. Hum Mutat 2000; 9:344-7. [PMID: 9101295 DOI: 10.1002/(sici)1098-1004(1997)9:4<344::aid-humu7>3.0.co;2-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
delta-Thalassemia reduces the expected HbA2 percentage, altering the normal as well as the beta-thalassemia trait phenotype. An attempt to elucidate the molecular basis of delta-thalassemia in the Greek population, revealed two cases with unknown molecular defects that presented low levels of HbA2 (about 1.5%). DNA sequence analysis of delta-globin gene identified two "novel" mutations in the coding regions of the gene; the cd11 (GTC-->GGC) resulting in the substitution of valine for glycine (:HbA2-Pylos) and the cd85(TTT-->TCT) resulting in the substitution of phenylalanine for serine (:HbA2-Etolia). Because these mutations are localized at the helical positions A8 and F1 of the HbA2 respectively, they potentially cause molecular instability of the tetramer, thus leading to reduced HbA2 percentage.
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Affiliation(s)
- O Drakoulakou
- Laikon General Hospital, Center for Thalassemias, Athens, Greece
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14
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Papadakis M, Papapanagiotou E, Loutradi-Anagnostou A. Scanning method to identify the molecular heterogeneity of delta-globin gene especially in delta-thalassemias: detection of three novel substitutions in the promoter region of the gene. Hum Mutat 2000; 9:465-72. [PMID: 9143928 DOI: 10.1002/(sici)1098-1004(1997)9:5<465::aid-humu14>3.0.co;2-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A scanning strategy for the detection of delta-globin gene mutations and polymorphisms is presented. This procedure is based on the denaturing gradient gel electrophoresis (DGGE) of four different artificially amplified DNA fragments which cover the promoter, the exons, as well as IVS I of the reported gene. To estimate the efficiency and sensitivity of the proposed procedure, we analysed the appropriate controls of delta-thalassemic carriers, uncharacterised delta-thalassemias and cases with normal hematological phenotype, but slightly increased (up to 3.5%) HbA2. DGGE results permitted the identification of delta-globin gene mutations and the polymorphism -199 (T-->C). Three novel base substitutions inside the promoter region of the gene [-65 (A-->G), -55 (T-->C), -36 (C-->A)], were also revealed. These changes are either linked in cis with other mutations or are responsible for thalassemias or for positive regulatory effect in delta-globin gene expression. The proposed experimental strategy consists of an accurate, rapid, safe and inexpensive screening procedure for establishing the molecular basis of delta-globin gene defects, suitable for the application for both research and diagnostics.
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Affiliation(s)
- M Papadakis
- Laikon General Hospital, Center for Thalassemias, Unit of Prenatal Diagnosis, Athens, Greece
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15
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Abstract
The beta-thalassemia is probably the most extensively studied genetic disease. Essentially any molecular defect that has been first described in association with the globin genes has been later implicated as a molecular determinant of newly discovered genes. Accordingly, the thalassemias have always represented a model genetic disease, especially in relation to the development of programs for population screening, genetic counseling and prenatal diagnosis. Here we will review the present knowledge on the genetics of thalassemia and of the relevant modifying factors. Major categories of the carrier state, the genotypes, the clinical phenotypes and the correlation between genotype and phenotype will be discussed.
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Affiliation(s)
- A Cao
- Istituto di Clinica e Biologia dell'Età Evolutiva, Università di Cagliari, Italy.
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16
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Waye JS, Borys S, Eng B, Patterson M, Chui DH, Badr El-Din OM, Aref MK, Afify Z. Spectrum of beta-thalassemia mutations in Egypt. Hemoglobin 1999; 23:255-61. [PMID: 10490138 DOI: 10.3109/03630269909005706] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- J S Waye
- Provincial Hemoglobinopathy, DNA Diagnostic Laboratory, McMaster University Medical Centre, Hamilton, Ontario, Canada.
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17
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Abstract
A complete spectrum of genetic lesions affecting the beta-globin gene giving rise to a complete spectrum of phenotypic severity is described. Although most of the molecular lesions involve the structural beta gene directly, some down regulate the gene through in-cis effects at a distance while trans-acting factors are implicated in a few cases. The remarkable phenotypic diversity can be related ultimately to the degree of alpha-globin-beta-globin chain imbalance and arises from variability of mutations affecting the beta gene itself and from interactions with other genetic loci, such as the alpha- and gamma-globin genes. The presence of other interacting loci is implicated by their interactions in increasing gamma gene expression or by an increased proteolytic capacity of the erythroid precursors. It is hoped that observations from the genotype-phenotype relationship might form the basis for a comprehensive diagnostic database that will be useful not only for genetic counselling and prenatal diagnosis but also for providing prognostic information for decision making in bone marrow transplantation and gene therapy programmes in the future. However, it is clear from recent analyses that, apart from the two categories of triplicated alpha genes with heterozygous beta-thalassaemia and inheritance of mild beta(+)-thalassaemia alleles, it is still not possible to predict consistently phenotype from alpha and beta genotypes alone owing to the influence of the other modulating factors, some implicated (such as inheritance of hereditary persistence of fetal haemoglobin) and others as yet unidentified.
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Affiliation(s)
- S L Thein
- MRC Molecular Haematology Unit, John Radcliffe Hospital, Headington, Oxford, UK
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18
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Affiliation(s)
- T H Huisman
- Editorial Office, HEMOGLOBIN, Medical College of Georgia, Augusta 30912-2100, USA
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19
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Ho PJ, Hall GW, Luo LY, Weatherall DJ, Thein SL. Beta-thalassaemia intermedia: is it possible consistently to predict phenotype from genotype? Br J Haematol 1998; 100:70-8. [PMID: 9450794 DOI: 10.1046/j.1365-2141.1998.00519.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Eighty-seven patients with beta thalassaemia of intermediate severity were investigated in our Unit to determine whether it is possible to consistently predict phenotypic severity from genotypic factors. The subjects were from the following ethnic backgrounds: Asian Indian (35.1%), Middle Eastern (24.3%), Mediterranean (21.6%), Northern European (14.9%) and South-East Asian/Chinese (4.1%). There was a wide spectrum of phenotypic severity; 49 had mild disease, 22 moderate and 16 severe disease. 22/87 patients had inherited only a single copy of a beta-thalassaemia allele, of whom 11 had also co-inherited triplicated alpha genes (alpha alpha alpha/alpha alpha or alpha alpha alpha/alpha alpha alpha) and seven had dominantly inherited beta thalassaemia. In four of the heterozygotes no explanation was found for the thalassaemia-intermedia phenotype. 65/87 patients were homozygous or compound heterozygous for 26 mutations (40 genotypes) which ranged from very mild beta+ to beta0 thalassaemia alleles. All patients with two mild or very mild beta+ thalassaemia alleles had mild to moderate disease. Although concurrent inheritance of extra alpha genes with heterozygous beta thalassaemia results in thalassaemia intermedia, the disease is mild. Co-inheritance of alpha thalassaemia as a modulating factor was not evident in this cohort of patients. Presence of the in-cis Xmn I-Ggamma site was a modulating factor but insufficient to explain the high fetal haemoglobin levels encountered. In conclusion, apart from the two categories of triplicated alpha genes with heterozygous beta thalassaemia and inheritance of mild beta+ thalassaemia alleles, it was not possible to consistently predict phenotype from alpha and beta genotypes alone, due to the influence of modulating factors, some implicated (such as inheritance of HPFH determinants) and others as yet unidentified.
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Affiliation(s)
- P J Ho
- MRC Molecular Haematology Unit, Institute of Molecular Medicine, Headington, Oxford
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20
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Trifillis P, Adachi K, Yamaguchi T, Schwartz E, Surrey S. Expression studies of delta-globin gene alleles associated with reduced hemoglobin A2 levels in Greek Cypriots. J Biol Chem 1996; 271:26931-8. [PMID: 8900178 DOI: 10.1074/jbc.271.43.26931] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We previously identified five delta-globin gene alleles associated with reduced hemoglobin (Hb) A2 (Trifillis, P., Ioannou, P., Schwartz, E., and Surrey, S. (1991) Blood 78, 3298-3305). We have now evaluated functional consequences of the changes after expression in COS-1 cells to monitor effects on RNA splicing. In addition, variant Hb A2 tetramers were expressed in yeast to assess effects of amino acid changes on oxygen binding and stability to heat and mechanical agitation. The G --> T change at codon 27 and the A --> G change in IVS-2 both affect RNA splicing, whereas the C --> T change at codon 97 and the AT deletion in IVS-2 have no effect. Oxygen equilibrium curves of the Hb A2 variants expressed in yeast were similar to that of wild type Hb A2. None of the three variant Hb A2 tetramers (Thr --> Ile at codon 4 (Hb deltaT4I), Ala --> Ser at codon 27 (Hb deltaA27S), and Arg --> Cys at codon 116 (Hb deltaR116C)) showed decreased heat stability compared with Hb A2, whereas the Hb deltaT4I variant showed highest instability to mechanical agitation. Co-expression in yeast of alpha-globin chain and the delta-chain variant containing a Leu --> Pro change at codon 141 yielded no identifiable tetramers, suggesting lack of assembly or severe tetramer instability. These studies show the probable cause for decreased Hb A2 for two alleles is due to defective splicing, whereas decreased protein stability, increased tetramer association with red cell membranes, increased interdisulfide bond formation of delta-chains, which inhibits assembly with alpha-chains, and/or reduced assembly is suggested for the other three alleles.
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Affiliation(s)
- P Trifillis
- Division of Hematology, Abramson Pediatric Research Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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21
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Affiliation(s)
- E Baysal
- Department of Biochemistry and Molecular Biology Medical College of Georgia, Augusta 30912-2100, USA
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22
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Oggiano L, Guiso L, Frogheri L, Loudianos G, Pistidda P, Rimini E, Pirastu M, Cao A, Longinotti M. A novel Mediterranean "delta beta-thalassemia" determinant containing the delta (+) 27 and beta (0) 39 point mutations in cis. Am J Hematol 1994; 45:81-4. [PMID: 7504402 DOI: 10.1002/ajh.2830450113] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The term delta beta-thalassemia with normal HbF has been recently proposed to define heterogenous delta and beta globin gene molecular defects involving the same chromosome in cis. Here, we describe a Sardinian family in which three members showing microcytosis, border-line HbA2 levels and normal HbF proved to be heterozygotes for delta(+) 27 and beta(0) 39 point mutations in cis by allele specific oligonucleotide hybridization as well as by ECO 0 109 I endonuclease digestion and electrophoresis. As some of these beta-thalassemia carriers shows normal HbA2 levels, knowledge of the molecular basis of this novel delta beta-thalassemia silent phenotype would be useful in thalassemia screening and genetic counselling.
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Affiliation(s)
- L Oggiano
- Istituto di Ematologia ed Endocrinologia, Università degli Studi Sassari, Italy
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23
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Gasperini D, Perseu L, Cossu P, Podda R, Cao A, Galanello R. A novel delta O-thalassemia mutation: TGG-->TAG (TRP-->STOP) at codon 37. Hum Mutat 1994; 3:71-2. [PMID: 8118467 DOI: 10.1002/humu.1380030114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- D Gasperini
- Istituto di Clinica e Biologia dell'Età Evolutiva, Università di Cagliari, Italy
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24
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Affiliation(s)
- S L Thein
- MRC Molecular Haematology Unit, Radcliffe Hospital, Oxford, U.K
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25
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Affiliation(s)
- T H Huisman
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta 30912-2100
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26
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Trent RJ, Thein SL. Detection of beta and delta globin gene mutations by PCR and direct DNA sequencing in an individual with normal HbA2 beta thalassemia. Pathology 1992; 24:15-8. [PMID: 1349739 DOI: 10.3109/00313029209063614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Normal HbA2 beta thalassemia in a Greek individual was shown to be due to co-inheritance of beta and delta thalassemias. The genetic defects were characterized by enzymatic amplification of the beta and delta globin genes and direct genomic sequencing. Two children with a typical high HbA2 beta thalassemia trait had inherited the beta thalassemia allele whilst a third child had low-normal HbA2 associated with delta+ thalassemia. Segregation patterns confirmed that the delta+/beta zero thalassemia defects were present in trans.
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Affiliation(s)
- R J Trent
- MRC Molecular Hematology Unit, John Radcliffe Hospital, Oxford, U.K
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27
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Loudianos G, Murru S, Ristaldi MS, Cossu P, Pilia G, Porcu S, Sciarratta GV, Parodi MI, Cao A, Pirastu M. A novel delta-thalassemia mutation A G-->C substitution at codon 30 of the delta-globin gene in a person of southern Italian origin. Hum Mutat 1992; 1:169-71. [PMID: 1301204 DOI: 10.1002/humu.1380010215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- G Loudianos
- Istituto di Clinica e Biologia dell'Età Evolutiva, Università degli Studi di Cagliari, Italy
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