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Conference Paper: A novel beta-delta globin gene fusion leads to over-expression of delta globin chain and a mild thalassemia intermedia phenotype when co-inherited with beta-zero thalassemia

TitleA novel beta-delta globin gene fusion leads to over-expression of delta globin chain and a mild thalassemia intermedia phenotype when co-inherited with beta-zero thalassemia
Authors
Issue Date2006
PublisherAmerican Society of Hematology. The Journal's web site is located at http://www.bloodjournal.org/
Citation
The 48th Annual Meeting and Expositions of the American Society of Hematology (ASH 2006), Orlando, FL., 9-12 December 2006. In Blood, 2006, v. 108 n. 11, p. 1587 How to Cite?
AbstractAnti-Lepore hemoglobins are rare βδ fusion variants that arise from nonhomologous crossover during meiosis, resulting in a δ-βδ-β configuration in the β globin cluster on the short arm of chromosome 11. No such variant has previously been reported in Chinese. We studied 2 unrelated Chinese families with anti-Lepore due to a novel βδ fusion. A moderate increase of Hb A2 to between 16.8 and 19.2% of total Hb was seen in 4 clinically and hematologically normal carriers, while in 1 patient with concurrent β thalassemia allele and mild thalassemia intermedia phenotype, the Hb A2 was markedly raised to 42.2%. Potential βδ fusion gene was amplified using PCR with primer 5′ to β globin gene Cap site and 3′ to δ globin gene poly A region in these 5 subjects. Direct sequencing of the PCR products revealed a crossover between the β and δ globin gene within a 54 bp region spanning the junction of CAP and exon 1 in all 5 subjects. Active transcription of this novel βδ fusion gene was studied in 2 subjects (1 normal carrier and the patient with thalassemia intermedia). Using primer pair 5′ to β globin gene Cap site and at the 3′ end of δ globin gene exon 3, a 655 bp PCR product was obtained from cDNA in both subjects. Direct sequencing confirmed the presence of a βδ fusion mRNA. The predicted protein product of this fusion gene was identical to δ globin, since only the 5′ untranslated region was β specific. Determination of α/β mRNA ratios by quantitative real-time PCR was performed in 2 normal carriers (ratio 3.28 and 3.95) and the patient with thalassemia intermedia (ratio 25.59). These were compared with ratios ± standard deviation from 20 normal controls (1.92±0.55), 5 unrelated patients with β thalassaemia minor (17.23±5.38) and 3 unrelated patients with β thalassemia major (139.21±39.50). Mild down-regulation of the β gene in cis due to this interposed βδ fusion gene was demonstrated. Although heterozygotes of this novel anti-Lepore Hb had normal red cell indices and were clinically silent, compound heterozygotes with β0 mutation in trans produced a mild thalassemia intermedia phenotype with a markedly raised Hb A2 level that might mimic clinically mild Hb E-β+ thalassemia. Awareness of this new anti-Lepore Hb will help to resolve diagnostic problems in regions with significant prevalence of globin disorders. © 2006, The American Society of Hematology
Persistent Identifierhttp://hdl.handle.net/10722/104618
ISSN
2015 Impact Factor: 11.841
2015 SCImago Journal Rankings: 6.395

 

DC FieldValueLanguage
dc.contributor.authorSo, JCCen_HK
dc.contributor.authorChan, AYYen_HK
dc.contributor.authorTsang, STYen_HK
dc.contributor.authorLee, ACWen_HK
dc.contributor.authorAu, WYen_HK
dc.contributor.authorMa, ESKen_HK
dc.contributor.authorChan, LCen_HK
dc.date.accessioned2010-09-25T22:00:28Z-
dc.date.available2010-09-25T22:00:28Z-
dc.date.issued2006en_HK
dc.identifier.citationThe 48th Annual Meeting and Expositions of the American Society of Hematology (ASH 2006), Orlando, FL., 9-12 December 2006. In Blood, 2006, v. 108 n. 11, p. 1587en_HK
dc.identifier.issn0006-4971-
dc.identifier.urihttp://hdl.handle.net/10722/104618-
dc.description.abstractAnti-Lepore hemoglobins are rare βδ fusion variants that arise from nonhomologous crossover during meiosis, resulting in a δ-βδ-β configuration in the β globin cluster on the short arm of chromosome 11. No such variant has previously been reported in Chinese. We studied 2 unrelated Chinese families with anti-Lepore due to a novel βδ fusion. A moderate increase of Hb A2 to between 16.8 and 19.2% of total Hb was seen in 4 clinically and hematologically normal carriers, while in 1 patient with concurrent β thalassemia allele and mild thalassemia intermedia phenotype, the Hb A2 was markedly raised to 42.2%. Potential βδ fusion gene was amplified using PCR with primer 5′ to β globin gene Cap site and 3′ to δ globin gene poly A region in these 5 subjects. Direct sequencing of the PCR products revealed a crossover between the β and δ globin gene within a 54 bp region spanning the junction of CAP and exon 1 in all 5 subjects. Active transcription of this novel βδ fusion gene was studied in 2 subjects (1 normal carrier and the patient with thalassemia intermedia). Using primer pair 5′ to β globin gene Cap site and at the 3′ end of δ globin gene exon 3, a 655 bp PCR product was obtained from cDNA in both subjects. Direct sequencing confirmed the presence of a βδ fusion mRNA. The predicted protein product of this fusion gene was identical to δ globin, since only the 5′ untranslated region was β specific. Determination of α/β mRNA ratios by quantitative real-time PCR was performed in 2 normal carriers (ratio 3.28 and 3.95) and the patient with thalassemia intermedia (ratio 25.59). These were compared with ratios ± standard deviation from 20 normal controls (1.92±0.55), 5 unrelated patients with β thalassaemia minor (17.23±5.38) and 3 unrelated patients with β thalassemia major (139.21±39.50). Mild down-regulation of the β gene in cis due to this interposed βδ fusion gene was demonstrated. Although heterozygotes of this novel anti-Lepore Hb had normal red cell indices and were clinically silent, compound heterozygotes with β0 mutation in trans produced a mild thalassemia intermedia phenotype with a markedly raised Hb A2 level that might mimic clinically mild Hb E-β+ thalassemia. Awareness of this new anti-Lepore Hb will help to resolve diagnostic problems in regions with significant prevalence of globin disorders. © 2006, The American Society of Hematology-
dc.languageengen_HK
dc.publisherAmerican Society of Hematology. The Journal's web site is located at http://www.bloodjournal.org/-
dc.relation.ispartofBlooden_HK
dc.rightsBlood. © American Society of Hematology.-
dc.titleA novel beta-delta globin gene fusion leads to over-expression of delta globin chain and a mild thalassemia intermedia phenotype when co-inherited with beta-zero thalassemiaen_HK
dc.typeConference_Paperen_HK
dc.identifier.emailSo, JCC: scc@pathology.hku.hken_HK
dc.identifier.emailTsang, STY: stella@pathology.hku.hken_HK
dc.identifier.emailMa, ESK: eskma@hksh.comen_HK
dc.identifier.emailChan, LC: chanlc@hkucc.hku.hken_HK
dc.identifier.authoritySo, JCC=rp00391en_HK
dc.identifier.hkuros125342en_HK
dc.identifier.volume108en_HK
dc.identifier.issue11-
dc.identifier.spage1587-
dc.identifier.epage1587-
dc.publisher.placeUnited States-

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