Sickle-cell disease epidemiology and demographics
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shyam Patel [2]
Overview
Certain races and geographic territories are more commonly affected by sickle cell disease. These geographic areas include Africa, India, and Middle East.
Epidemiology and Demographics
Sickle cell disease is known to have a high prevalence in Africa (specifically the sub-Saharan region), India, and the Middle East. Different regions of the world display different frequencies of genotypes of the various sickle cell subtypes. Sickle cell disease largely affects people of African descent. The incidence of sickle cell disease is 312,000 per year worldwide. Among these, 76% (236,000 people) are born in sub-Saharan Africa.[1] The current prevalence of sickle cell disease is 20 million, and nearly 50% of affected people are in Africa. India comprises 5-10 million people with sickle cell disease. Regarding allele frequencies, the S (glutamic acid to valine) and C (glutamic acid to lysine) alleles are highest in Africa.[2] In a study of three cohorts in Nigeria and Sudan, the frequency of HbSS was 88-96%. The frequency of HbSC was 4-12%.[1] It affects 1 in 400 African Americans, and a total of 89,000 Americans.[3]
People from India also have higher frequencies of sickle cell alleles compared to others. Compared to people from Africa, those from India have a lower frequency of the HbSS genotype (30-70%) and a higher frequency of sickle cell-beta-thalassemia (HbSB) genotype.[1] The heterozygote prevalence (HbAS) in India of sickle disease varies from 1-40%. Certain tribal populations in India have high prevalences of sickle cell trait and/or disease. For example, Madhya Pradesh has the highest prevalence, with more tan 960000 heterozygotes and nearly 68000 homozogotes. [4]
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4510747/bin/IJMR-141-509-g001.jpg Frequency of sickle cell trait in various provinces of India.[4]
The frequency of sickle cell alleles are highest in regions of the country where malaria is endemic.[1] The reason for this is that, from an evolutionary standpoint, the presence of sickle cell alleles and abnormal hemoglobin confers a protective advantage against malaria. The causative agents of malaria, Plasmodium, is less likely to infect diseased red blood cells.[1] This concept is known as the heterozygote advantage.
Besides Africa and India, other geographic regions are affected by particular sickle cell phenotypes. The HbSC phenotype. for example, is prevalent in geographic areas such as Burkina Faso.[1] HbS-beta-thalassemia is commonly found in Greece.[1] The nomenclature of certain sickle cell hemoglobinopathies and haplotypes is based on the region in which the prevalence is high. For example, hemoglobin Senegal has been found in Senegal. Others include hemoglobin Benin and hemoglobin Bantu.[2]
The prevalence of sickle cell disease in the United States is relatively low: approximately 100,000 people are affected.[1] However, sickle cell disease poses a significant challenge to the American health care system. There is a high frequency of emergency department visits by patients with sickle cell disease. Over a two-year period, there were more than 97,000 visits amongst 8 states.[3] Among these visits, 52,107 warranted hospitalization.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Saraf SL, Molokie RE, Nouraie M, Sable CA, Luchtman-Jones L, Ensing GJ; et al. (2014). "Differences in the clinical and genotypic presentation of sickle cell disease around the world". Paediatr Respir Rev. 15 (1): 4–12. doi:10.1016/j.prrv.2013.11.003. PMC 3944316. PMID 24361300.
- ↑ 2.0 2.1 Makani J, Ofori-Acquah SF, Nnodu O, Wonkam A, Ohene-Frempong K (2013). "Sickle cell disease: new opportunities and challenges in Africa". ScientificWorldJournal. 2013: 193252. doi:10.1155/2013/193252. PMC 3988892. PMID 25143960.
- ↑ 3.0 3.1 Brandow AM, Liem R (2011). ""Sickle Cell Disease in the Emergency Department: Atypical Complications and Management"". Clin Pediatr Emerg Med. 12 (3): 202–212. doi:10.1016/j.cpem.2011.07.003. PMC 3172721. PMID 21927581.
- ↑ 4.0 4.1 Colah RB, Mukherjee MB, Martin S, Ghosh K (2015). "Sickle cell disease in tribal populations in India". Indian J Med Res. 141 (5): 509–15. PMC 4510747. PMID 26139766.