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Seria E, Galea G, Borg J, Schembri K, Grech G, Tagliaferro SS, Felice A. Novel leukocyte-depleted platelet-rich plasma-based skin equivalent as an in vitro model of chronic wounds: a preliminary study. BMC Mol Cell Biol 2021; 22:28. [PMID: 33971814 PMCID: PMC8111747 DOI: 10.1186/s12860-021-00366-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chronic leg ulcerations are associated with Haemoglobin disorders, Type2 Diabetes Mellitus, and long-term venous insufficiency, where poor perfusion and altered metabolism develop into a chronic inflammation that impairs wound closure. Skin equivalent organotypic cultures can be engineered in vitro to study skin biology and wound closure by modelling the specific cellular components of the skin. This study aimed to develop a novel bioactive platelet-rich plasma (PRP) leukocyte depleted scaffold to facilitate the study of common clinical skin wounds in patients with poor chronic skin perfusion and low leukocyte infiltration. A scratch assay was performed on the skin model to mimic two skin wound conditions, an untreated condition and a condition treated with recombinant tumour necrotic factor (rTNF) to imitate the stimulation of an inflammatory state. Gene expression of IL8 and TGFA was analysed in both conditions. Statistical analysis was done through ANOVA and paired student t-test. P < 0.05 was considered significant. RESULTS A skin model that consisted of a leukocyte-depleted, platelet-rich plasma scaffold was setup with embedded fibroblasts as dermal equivalents and seeded keratinocytes as multi-layered epidermis. Gene expression levels of IL8 and TGFA were significantly different between the control and scratched conditions (p < 0.001 and p < 0.01 respectively), as well as between the control and treated conditions (p < 0.01 and p < 0.001 respectively). The scratch assay induced IL8 upregulation after 3 h (p < 0.05) which continued to increase up to day 1 (p < 0.05). On the other hand, the administration of TNF led to the downregulation of IL8 (p < 0.01), followed by an upregulation on day 2. IL8 gene expression decreased in the scratched condition after day 1 as the natural healing process took place and was lower than in the treated condition on day 8 (p < 0.05). Both untreated and treated conditions showed a downregulation of TGFA 3 h after scratch when compared with the control condition (p < 0.01). Administration of rTNF showed significant downregulation of TGFA after 24 h when compared with the control (p < 0.01) and treated conditions (p < 0.05). CONCLUSION This study suggests that a leukocyte-depleted PRP-based skin equivalent can be a useful model for the in vitro study of chronic skin wounds related to poor skin perfusion.
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Affiliation(s)
- Elisa Seria
- Department of Physiology and Biochemistry and Centre of Molecular Medicine and Biobanking, Faculty of Medicine and Surgery, University of Malta, Msida, MSD2080, Malta.
| | - George Galea
- National Blood Transfusion Centre and Department of Pathology, University of Malta, Msida, MSD2080, Malta
| | - Joseph Borg
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, MSD2080, Malta
| | - Kevin Schembri
- Department of Surgery, Faculty of Medicine and Surgery, University of Malta Medical School and Mater Dei Hospital, Msida, MSD2080, Malta
| | - Gabriella Grech
- Department of Surgery, Faculty of Medicine and Surgery, University of Malta Medical School and Mater Dei Hospital, Msida, MSD2080, Malta
| | - Sarah Samut Tagliaferro
- Department of Physiology and Biochemistry and Centre of Molecular Medicine and Biobanking, Faculty of Medicine and Surgery, University of Malta, Msida, MSD2080, Malta
| | - Alexander Felice
- Department of Physiology and Biochemistry and Centre of Molecular Medicine and Biobanking, Faculty of Medicine and Surgery, University of Malta, Msida, MSD2080, Malta
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Seria E, Samut Tagliaferro S, Cutajar D, Galdies R, Felice A. Immunoglobulin G in Platelet-Derived Wound Healing Factors. BIOMED RESEARCH INTERNATIONAL 2021; 2021:4762657. [PMID: 33575328 PMCID: PMC7861922 DOI: 10.1155/2021/4762657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 12/03/2020] [Accepted: 01/13/2021] [Indexed: 11/17/2022]
Abstract
We intended to reformulate an existing platelet-derived wound healing formula to target each phase of the healing wound with the appropriate phase-specific molecules. A decreased perfusion of the skin, often associated with conditions such as thalassemia, sickle cell disease, diabetes mellitus, and chronic vascular disease, is the most common etiology of cutaneous ulcers and chronic wounds. We had previously shown that a PDWHF topically applied to a chronic nonhealing ulcer of a β-thalassemia homozygote stimulated and accelerated closure of the wound. The PDWHF was prepared from a pooled platelet concentrate of a matching blood group, consisting of a combination of platelet α-granule-derived factors. Processing of the apheresis-pooled platelets yielded various amounts of proteins (3.36 g/mL ± 0.25 (SD) (N = 10)) by the better lysis buffer method. Immunoglobulin G was found to be the most abundant α-granule-secreted protein. Equally broad quantities of the IgG (10.76 ± 12.66% (SD) (N = 10)) and IgG/albumin ratios (0.6 ± 0.4 (SD) (N = 10)) were quantified. We have developed a method using a reformulated lysis buffer followed by size exclusion chromatography and affinity chromatography to extract, identify, quantify, and purify IgG from activated platelets. IgG purification was confirmed by Western blot and flow cytometry. It was thought unlikely that the platelet IgG could be accounted for by adsorption of plasma protein, though the variable quantities could account for diversity in wound healing rates. The IgG could protect the wound even from subclinical infections and functionally advance healing. It may be useful in the management of skin ulcers in the early phase of wound healing.
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Affiliation(s)
- Elisa Seria
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, Centre of Molecular Medicine and Biobanking, University of Malta and Division of Pathology, Mater Dei Hospital, Malta MSD2080
| | - Sarah Samut Tagliaferro
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, Centre of Molecular Medicine and Biobanking, University of Malta and Division of Pathology, Mater Dei Hospital, Malta MSD2080
| | - Doreen Cutajar
- Department of Surgery, Faculty of Medicine and Surgery, University of Malta Medical School and Mater Dei Hospital, Malta MSD2080
| | - Ruth Galdies
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, Centre of Molecular Medicine and Biobanking, University of Malta and Division of Pathology, Mater Dei Hospital, Malta MSD2080
| | - Alex Felice
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, Centre of Molecular Medicine and Biobanking, University of Malta and Division of Pathology, Mater Dei Hospital, Malta MSD2080
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Khan AM, Al-Sulaiti AM, Younes S, Yassin M, Zayed H. The spectrum of beta-thalassemia mutations in the 22 Arab countries: a systematic review. Expert Rev Hematol 2020; 14:109-122. [PMID: 33317346 DOI: 10.1080/17474086.2021.1860003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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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Affiliation(s)
- Aisha Moeen Khan
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University , Doha, Qatar
| | - Asma Mohammed Al-Sulaiti
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University , Doha, Qatar
| | - Salma Younes
- Translational Research Institute, Women's Wellness and Research Center, Hamad Medical Corporation , Qatar
| | - Mohamed Yassin
- Department of Hematology and BMT, National Center for Cancer Care and Research, Hamad Medical Corporation , Doha, Qatar
| | - Hatem Zayed
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University , Doha, Qatar
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Pace NP, Rizzo C, Abela A, Gruppetta M, Fava S, Felice A, Vassallo J. Identification of an HNF1A p.Gly292fs Frameshift Mutation Presenting as Diabetes During Pregnancy in a Maltese Family. CLINICAL MEDICINE INSIGHTS-CASE REPORTS 2019; 12:1179547619831034. [PMID: 30814848 PMCID: PMC6383084 DOI: 10.1177/1179547619831034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 01/18/2019] [Indexed: 12/15/2022]
Abstract
The diagnosis of maturity onset diabetes of the young (MODY) is a challenging
process in view of the extensive clinical and genetic heterogeneity of the
disease. Mutations in the gene encoding hepatocyte nuclear factor 1α
(HNF1A) are responsible for most forms of monogenic
diabetes in Northern European populations. Genetic analysis through a
combination of whole exome sequencing and Sanger sequencing in three Maltese
siblings and their father identified a rare duplication/frameshift mutation in
exon 4 of HNF1A that lies within a known mutational hotspot in
this gene. In this report, we provide the first description of an
HNF1A-MODY3 phenotype in a Maltese family. The findings
reported are relevant and new to a regional population, where the epidemiology
of atypical diabetes has never been studied before. This report is of clinical
interest as it highlights how monogenic diabetes can be misdiagnosed as either
type 1, type 2, or gestational diabetes. It also reinforces the need for a
better characterisation of monogenic diabetes in Mediterranean countries,
particularly in island populations such as Malta with a high prevalence of
diabetes.
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Affiliation(s)
- Nikolai Paul Pace
- Centre for Molecular Medicine and Biobanking, University of Malta, Msida, Malta
| | | | - Alexia Abela
- Department of Medicine, Mater Dei Hospital, Msida, Malta
| | - Mark Gruppetta
- Department of Medicine, Mater Dei Hospital, Msida, Malta
| | - Stephen Fava
- Department of Medicine, Mater Dei Hospital, Msida, Malta
| | - Alex Felice
- Centre for Molecular Medicine and Biobanking, University of Malta, Msida, Malta
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5
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Incidence of haemoglobinopathies in various populations — The impact of immigration. Clin Biochem 2009; 42:1745-56. [DOI: 10.1016/j.clinbiochem.2009.05.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Accepted: 05/22/2009] [Indexed: 11/19/2022]
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6
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Felice AE, Borg J, Pizzuto M, Cassar W, Galdies R, Wettinger SB, Pulis S, Hunter GJ, Caruana MR, Farrugia M, Scerri CA. A Review ofCis-TransInterplay Between DNA Sequences 5′ to theGγ- and β-Globin Genes Among Hb F-Malta-I Heterozygotes/Homozygotes and β-Thalassemia Homozygotes/Compound Heterozygotes, and the Effects of Hydroxyurea on the Hb F/F-Erythrocyte; the Need for Large Multicenter Trials. Hemoglobin 2009; 31:279-88. [PMID: 17486512 DOI: 10.1080/03630260701297261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The biosynthesis of Hb F in place of the deficient Hb A could be a suitable treatment for beta hemoglobinopathies. Among newborn Hb F-Malta-I heterozygotes, it could be shown that the XmnI sequence alone had little, if any effect on gamma-globin gene expression, but interplay with the (AT)(X)T(Y) sites in cis and in trans may occur. In contrast, while the XmnI sequence is clearly correlated with gamma-globin levels in anemic adult beta-thalassemia (thal) homozygotes, the effect on F-erythrocyte numbers and Hb F/F-erythrocyte appears independent of the (AT)(X)T(Y) sites. Even at levels of hydroxyurea (HU) as low as 1.65 mg/kg/day (vs. 10 mg/kg/day on the high dose regime) it can be shown that although even a small increase of Hb F could be obtained, the effect was rarely translated into an increase in circulating hemoglobin (Hb). In most cases, the elevated Hb F level was dependent on the XmnI sequence and was due to increased numbers of F-erythrocytes or Hb F/F-erythrocyte or both. It seems that the bone marrow of thalassemia homozygotes may be more sensitive to myelosuppression by HU possibly due to medullary inflammation. While the data are consistent with loop models of globin switching mechanisms, there is urgent need for large, hypothesis driven, multicenter trials of molecules that could maintain or re-induce high Hb F levels in beta-thal and subject to genetic and epigenetic constraints including inflammation.
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Affiliation(s)
- Alex E Felice
- Laboratory of Molecular Genetics, and Thalassemia and Molecular Genetics Clinic, Division of Pathology, St. Luke's Hospital, Department of Health, G'Mangia. Malta.
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7
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Pulis S, Scerri CA, Wismayer PS, Galdies R, Wettinger SB, Felice AE. Developmental Effect of theXmnI Site onGγ-Globin Gene Expression Among Newborn Hb F-Malta-I [Gγ117(G19)His→Arg, CAT→CGT] Heterozygotes and Adult β+-Thalassemia Homozygotes. Hemoglobin 2009; 31:71-82. [PMID: 17365007 DOI: 10.1080/03630260601057187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Hb F-Malta-I [Ggamma117(19)His-->Arg, CAT-->CGT] is a stable and benign variant of Hb F found in 1.8% of Maltese newborn. We studied 120 Hb F-Malta-I heterozygotes and four Hb F-Malta-I homozygotes. The mean proportion of Ggamma-F-Malta-I in Hb F was 0.26 +/- 0.03 for the Hb F-Malta-I heterozygotes and 0.58 +/- 0.06 for the Hb F-Malta-I homozygotes. The Hb F-Malta-I allele was shown to occur on a background of the common Mediterranean haplotype Va [+ + - - - - - + + -]. Furthermore, the common Mediterranean haplotypes Va, IIIb [- + + + - + + + + -], I [+ + - - - - - + + +] and II [- + - + + - + + + +] accounted for most (66.2%) of the wild-type alleles among the tested Hb F-Malta-I heterozygotes. Different genotypes at the 5' epsilon HincII, Ggamma and Agamma HindIII, and 3'psibeta HincII sites (but not at the 5' Ggamma XmnI site) were found to be linked to significant variations in the proportion of Ggamma-F-Malta-I and Ggamma-globins in the Hb F of newborn Hb F-Malta-I heterozygotes. Moreover, the 5' Ggamma XmnI site was found to be associated with variations in Hb F and Ggamma-globin levels in a population of adult Maltese beta-thalassemia (thal) homozygotes. This implies that a determinant linked to the XmnI site which effects Ggamma-globin gene expression is active in anemic adults but not in normal infants.
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Affiliation(s)
- Svetlana Pulis
- Laboratory of Molecular Genetics, Department of Physiology and Biochemistry, University of Malta, Msida, Malta.
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8
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Vella F. Development of biochemistry and molecular biology in Malta. IUBMB Life 2008; 60:260-1. [DOI: 10.1002/iub.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Talmaci R, Traeger-Synodinos J, Kanavakis E, Coriu D, Colita D, Gavrila L. Scanning of beta-globin gene for identification of beta-thalassemia mutation in Romanian population. J Cell Mol Med 2005; 8:232-40. [PMID: 15256071 PMCID: PMC6740280 DOI: 10.1111/j.1582-4934.2004.tb00278.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Beta-thalassemia is uncommon (0.5%) in the Romanian population, but it must be considered in the differential diagnosis of hypochromic anemia. The molecular characterization of beta-thalassemia is absolutely necessary for molecular diagnosis, as well as any genetic epidemiological study in this region. Molecular analyses consist of mutation detection by molecular scanning of beta-globin gene. This gene has 3 exons and 2 introns, involved in beta-thalassemic pathogenesis. Clinical application of DNA analysis on beta-thalassemic chromosomes allowed characterization of 29 persons with different beta-thalassemia mutations among 58 patients with anemia. The experimental strategy was based on sequential PCR amplification of most of the beta-globin gene and running on denaturing gradient gel electrophoresis of amplification products. Definitive characterization of mutations in samples identified with shifted DGGE patterns was performed ARMS-PCR and/or PCR-restriction enzyme analysis methods. Eight different beta-thalassemia alleles were identified, the most common being IVS I-110 (G-A) and cd 39 (C-T). Comparison of overall frequency of mutations in the neighboring countries, shows that these results are in the frame of overall distribution of these mutations in Mediterranean area, especially in Greece and in Bulgaria. Molecular diagnosis is useful for differentiating mild from severe alleles, for genetic counseling, as well as for mutation definition in carriers, identified by hematological analysis necessary for prenatal testing and genetic counseling.
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Affiliation(s)
- R Talmaci
- Human Genetics Department, Genetics Institute of Bucharest University, Aleea Portocalilor nr. 1-3, 76258, Bucharest, Romania
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Chan V, Wong MS, Ooi C, Chen FE, Chim CS, Liang RHS, Todd D, Chan TK. Can defects in transferrin receptor 2 and hereditary hemochromatosis genes account for iron overload in HbH disease? Blood Cells Mol Dis 2003; 30:107-11. [PMID: 12667993 DOI: 10.1016/s1079-9796(03)00013-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Iron overload was found to be the major cause of disability in Chinese HbH disease patients although they were not on regular blood transfusion. The transferrin receptor 2 (TFR2) and hereditary hemochromatosis (HFE) genes were examined to see if inheritance of these gene defects may be a possible cause of iron overload in 45 HbH patients. A novel intronic (IVS6 (+6) T-->A) mutation of the TFR2 gene was identified in one patient, and six others were found to carry a known missense mutation (exon 5, I238M) that was also present in one normal control subject. One HbH patient and one normal control carried the H63D mutation of the HFE gene. Since only eight out of 45 iron-overloaded HbH patients carry a defect in the TFR2 or HFE gene in the heterozygote state and their iron loading status was comparable to the matched controls without such defects, it would appear that the accumulation of excess iron in HbH disease is more likely a result of increase dietary absorption secondary to ineffective erythropoiesis.
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Affiliation(s)
- Vivian Chan
- University Department of Medicine, Queen Mary Hospital, Hong Kong, SAR China.
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Marwan MM, Scerri CA, Zarroag SO, Cao A, Kyrri A, Kalogirou E, Kleanthous M, Ioannou P, Angastiniotis M, Felice AE. Comparative in vivo expression of beta(+)-thalassemia alleles. Hemoglobin 1999; 23:221-9. [PMID: 10490134 DOI: 10.3109/03630269909005702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Double heterozygotes who inherit one abnormal though stable beta-globin variant in association with a molecularly identified beta(+)-thalassaemia allele provide unique opportunities to quantify the in vivo expression of particular beta(+)-thalassemia alleles. The globin products of the two alleles can be separated, quantified and the output of the beta(+)-thalassaemia allele expressed as the MCH-beta(A) in pg beta(A)-globin/beta(+)-thalassemia allele/RBC = 0.5 MCH x Hb A%. In this communication we provide new quantitative data on the expression of five mutations as follows: the beta(+)-87 (C-->G) = 3.8 pg beta(A)-globin/beta(+)-thalassemia allele/RBC (n = 1); the beta(+) IVS-I-1 (G-->A) = 0.2 pg beta(A)-globin/beta(+)-thalassemia allele/RBC (n = 1); the beta(+) IVS-I-6 (T-->C) = 2.9 pg beta(A)-globin/beta(+)-thalassemia allele/RBC (n = 7); the beta(+) IVS-I-110 (G-->A) = 1.1 pg beta(A)-globin/beta(+)-thalassemia allele/RBC (n = 13), and the beta(+) IVS-II-745 (C-->G) = 1.74 pg beta(A)-globin/beta(+)-thalassemia allele/RBC (n = 2). The values obtained are compared with those of other beta(+)-thalassemia alleles from the literature. It can be seen that the MCH-beta(A) value may be a correct index of thalassemia severity useful for the correlation of genotype with phenotype, and for understanding the effects of mutations in beta-globin genes on pathophysiologically meaningful beta-globin gene expression.
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Affiliation(s)
- M M Marwan
- Department of Pathology, University of Malta, Msida
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Alshinawi C, Scerri C, Galdies R, Aquilina A, Felice AE. Two new missense mutations (P134T and A244V) in the coagulation factor VII gene. Hum Mutat 1998; Suppl 1:S189-91. [PMID: 9452082 DOI: 10.1002/humu.1380110161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- C Alshinawi
- Department of Pathology, Medical School, University of Malta, Msida
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13
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Efremov DG, Dimovski AJ, Baysal E, Ye Z, Adekile AD, Ribeiro ML, Schiliro G, Altay C, Gürgey A, Efremov GD. Possible factors influencing the haemoglobin and fetal haemoglobin levels in patients with beta-thalassaemia due to a homozygosity for the IVS-I-6 (T-->C) mutation. Br J Haematol 1994; 86:824-30. [PMID: 7522523 DOI: 10.1111/j.1365-2141.1994.tb04837.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have collected haematological, haemoglobin (Hb) and DNA sequence data for 29 patients with a homozygosity for the IVS-I-6 (T-->C) mutation with the intention of identifying factors contributing to the observed variability in the severity of the disease. None of the patients had received blood transfusion therapy for at least 6 months prior to the study. Hb levels varied from 5.0 to 9.9 g/dl. Patients with high Hb F (more than 1.5 g/dl or > 20%) had high total Hb levels (7.5-9.7 g/dl) but some with low Hb F also had high total Hb levels; two had a concomitant alpha-thalassaemia-2 (alpha-thal-2) heterozygosity. An inverse correlation between the Hb F and Hb A2 levels was observed. The majority of the patients were homozygous for haplotype VI (49/58 chromosomes) but haplotypes IV (2/58) and VII (7/58) were also present. The only haplotype IV homozygote had high Hb F levels with high G gamma values and the C-->T mutation at position -158 in the G gamma promoter, while both high and low Hb F levels were observed among patients with haplotypes VI and VII. Analysis of sequence variations in regulatory regions included the 5' hypersensitive sites (HS) 4. 3 and 2 of the locus control region (LCR), the G gamma and A gamma 5' flanking regions, the second intervening sequence (IVS-II), and the 5' beta-globin gene region in two patients with high Hb F (one homozygote each for haplotypes VI and IV), and in two patients with low Hb F levels (one homozygote each for haplotypes VI and VII). Haplotype specific differences were observed in the LCR 5' HS-2 and in the G gamma and A gamma flanking and IVS-II regions; however, no differences were present between the low and high Hb F-producing haplotype VI chromosomes, suggesting a major role for factors which are not linked to the beta-globin gene cluster in mediating gamma-globin gene expression in patients with this type of beta-thal.
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Affiliation(s)
- D G Efremov
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta 30912-2100
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