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Ata F, Rahhal A, Malkawi L, Iqbal P, Khamees I, Alhiyari M, Yousaf Z, Qasim H, Alshurafa A, Sardar S, Javed S, Fernyhough L, Yassin M. Genotypic and Phenotypic Composition of Sickle Cell Disease in the Arab Population - A Systematic Review. Pharmgenomics Pers Med 2023; 16:133-144. [PMID: 36851992 PMCID: PMC9961577 DOI: 10.2147/pgpm.s391394] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 02/01/2023] [Indexed: 02/24/2023] Open
Abstract
Sickle cell disease (SCD) is a genetic disease influenced by ethnicity and regional differences in its clinical course. Recent advances in the management of SCD with newer therapies are being introduced to the Western population. However, many of these treatments are yet to be used in the Arabic SCD population. Understanding the genetic variations of SCD regionally is essential to anticipate the utilization of new treatments. This systematic review's main objective is to pool the available data on the genetic composition of SCD in the Arabic population. Data for 44,034 patients was extracted from 184 studies (11 case reports, 8 case series, 56 retrospectives, 107 prospective observational studies, and 2 clinical trials) using PubMed, Scopus, and Google Scholar. Male (49%) and female (51%) patients were equally reported wherever gender was available (N=13105). Various SCD genotypes were reported in a total of 14,257 patients, including Hb SS (77%) Hb Sβ0 (9.9%), and Hb Sβ+ (7.2%), while the rest of the genotypes, including HbSC, HbSD, HbSE, HbSO Arab, Hb S/α-Thal, Hb Sβ0 + α-Thal, and HBS Oman were individually reported in <4% of the cases. Major SCD complications in the Arab population included pain crises (48.25%) followed by neurological complications (33.46%), hepatobiliary complications (25.53%), musculoskeletal complications (24.73%), and hemolytic anemia (23.57%). The treatments reported for SCD included hydroxyurea (20%), blood transfusion (14.32%), and Deferasirox (3.03%). We did not find the use of stem cell transplantation or newer treatments such as L-Glutamine, Voxelotor, Crizanlizumab, or gene therapy reported in any of the studies included in our review. This review highlights the genetic makeup of SCD in Arab countries and its common phenotypic manifestations and will help direct further research on SCD in this region, especially concerning genetic therapy. Systematic Review Registration The protocol has been registered in the International Prospective Register of Systematic Reviews(PROSPERO):CRD42020218,666. https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=218666.
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Affiliation(s)
- Fateen Ata
- Department of Endocrinology, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
| | - Alaa Rahhal
- Department of Clinical Pharmacy, Hamad Medical Corporation, Doha, Qatar
| | - Lujain Malkawi
- Department of Internal Medicine, Faculty of Medicine, Jordan University of Science and Technology, Irbid, Jordan
| | - Phool Iqbal
- Department of Internal Medicine, Metropolitan Hospital, New York, NY, USA
| | - Ibrahim Khamees
- Department of Internal Medicine, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
| | - Mousa Alhiyari
- Department of Internal Medicine, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
| | - Zohaib Yousaf
- Department of Internal Medicine, Reading Hospital - Tower Health, West Reading, PA, USA
| | - Hana Qasim
- Department of Internal Medicine, UMKC School of medicine, Kansas, MO, USA
| | - Awni Alshurafa
- Department of Medical Oncology /Hematology, National Centre for Cancer Care and Research, Hamad Medical Corporation, Doha, Qatar
| | - Sundus Sardar
- Department of Medicine, Division of Nephrology, Pennsylvania State University College of Medicine, Hershey Medical Center, Hershey, PA, USA
| | - Saad Javed
- Department of Internal Medicine, Icahn school of medicine at Mount Sinai/Queens Hospital Center, New York, NY, USA
| | - Liam Fernyhough
- Department of Medical Oncology /Hematology, National Centre for Cancer Care and Research, Hamad Medical Corporation, Doha, Qatar.,Department of Medical Education, Weill Cornell Medicine - Qatar, Doha, Qatar
| | - Mohamed Yassin
- Department of Medical Oncology /Hematology, National Centre for Cancer Care and Research, Hamad Medical Corporation, Doha, Qatar
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Abstract
Sickle cell disease (SCD) is characterized by variable clinical outcomes, with some patients suffering life-threatening complications during childhood, and others living relatively symptom-free into old age. Because of this variability, there is an important potential role for precision medicine, in which particular different treatments are selected for different groups of patients. However, the application of precision medicine in SCD is limited by difficulties in identifying different prognostic groups and the small number of available treatments. The main genetic determinant of outcomes in SCD is the underlying β-globin genotype, with sickle cell anemia (HbSS) and hemoglobin SC disease (HbSC) forming the 2 major forms of the disease in most populations of African origin. Although there are clear differences in clinical outcomes between these conditions, treatments approaches are very similar, with little evidence on how to treat HbSC in particular. Other genomic information, such as the co-inheritance of α-thalassemia, or high fetal hemoglobin (HbF) levels, is of some prognostic value but insufficient to determine treatments. Precision medicine is further limited by the fact that the 2 main drugs used in SCD, penicillin and hydroxyurea, are currently recommended for all patients. Newer treatments, such as crizanlizumab and voxelotor, raise the possibility that groups will emerge who respond best to particular drugs or combinations. Perhaps the best current example of precision medicine in SCD is the selective use of blood transfusions as primary stroke prevention in children with evidence of cerebral vasculopathy. More precise treatments may emerge as we understand more about the pathology of SCD, including problems with erythropoiesis.
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Ahmed SG, Ibrahim UA. Non-S Sickling Hemoglobin Variants: Historical, Genetic, Diagnostic, and Clinical Perspectives. Oman Med J 2021; 36:e261. [PMID: 34113458 PMCID: PMC8170066 DOI: 10.5001/omj.2021.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Accepted: 01/16/2020] [Indexed: 01/19/2023] Open
Abstract
Apart from hemoglobin-S (HbS), there are other Hb variants (non-S sickling Hb variants) that cause sickle cell disease. However, the profiles of these non-S sickling Hb variants have neither been collated nor harmonized. A literature search revealed 14 non-S sickling Hb variants (HbC-Harlem, HbC-Ziguinchor, HbS-Travis, HbS-Antilles, HbS-Providence, HbS-Oman, HbS-Cameroon, HbS-South End, Hb Jamaica Plain, HbC-Ndjamena, HbS-Clichy, HbS-San Martin, HbS-Wake, and HbS-São Paulo). Generally, the non-S sickling Hb variants are double mutants with the HbS mutation (GAG>GTG: βGlu6Val) and additional β-chain mutations. Consequently, non-S sickling Hb variants give positive solubility and sickling tests, but they differ from HbS with respect to stability, oxygen affinity, and electro-chromatographic characteristics. Similarities and discrepancies between HbS and non-S sickling Hb variants create diagnostic pitfalls that can only be resolved by elaborate electro-chromatographic and/or genetic tests. It is therefore imperative that tropical hematologists should have a thorough understanding of these atypical sickling Hb variants. Collated and harmonized appraisal of the non-S sickling Hb variants have not been previously undertaken. Hence, this paper aims to provide a comprehensive but concise historical, genetic, comparative, diagnostic, and clinical overview of non-S sickling Hb variants. The elaborate techniques often required for precise diagnosis of non-S sickling Hb variants are regrettably not readily available in low resource tropical countries, which paradoxically carry the heaviest burden of sickling disorders. We strongly recommend that tropical countries should upgrade their diagnostic laboratory facilities to avoid misdiagnosis of these atypical Hb mutants.
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Affiliation(s)
- Sagir G Ahmed
- Department of Hematology, Aminu Kano Teaching Hospital, Kano State, Nigeria
| | - Umma A Ibrahim
- Department of Pediatrics, Aminu Kano Teaching Hospital, Kano State, Nigeria
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