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The Type of SCD Depends on the Mutation
Sickle Cell Traits vs SCD Genotypes1,3-6
Sickle Cell Trait
Individuals with sickle cell trait inherit 1 mutant allele (Hbs)
- ~8% of African Americans are sickle cell trait carriers1
Sickle Cell Anemia
Individuals with sickle cell anemia inherit 2 HbS alleles
- ~74%-76%* of SCD population4,5
- ~70% are of African ancestry4,5
Other SCD Genotypes
Individuals inherit 1 HbS allele and another mutant Hb allele
5 different subtypes, depending on other mutation
- HbSC represents ~18%-24% of SCD population4,5*
- ~25%-30% are of African ancestry
- HbSβ0-thalassemia represents ~1%-6% of SCD population4,5*
- Most prevalent in people of Eastern Mediterranean or Indian descent
- HbSβ+-thalassemia represents ~1%-6% of SCD population4,5*
- Most prevalent in people of Eastern Mediterranean or Indian descent
- HbSD represents 1.3% of SCD population5*
- Most prevalent in northern India but occurs worldwide
- HbSα-thalassemia6
- ~40% are of African ancestry
- ~45% are of South East Asian ancestry
*Based on 3 large multicenter cohorts of patients with SCD of predominantly African ancestry in the Americas and the United Kingdom.5
1. Steinberg MH. Sickle cell disease and associated hemoglobinopathies. In: Goldman L, Ausiello D, eds, Cecil Medicine, 23rd ed. Philadelphia, PA; Saunders Elsevier; 2008:1217-1226. 2. Kalpatthi R, Novelli EM. Measuring success: utility of biomarkers in sickle cell disease clinical trials and care. Hematology Am Soc Hematol Educ Program. 2018. 2018;2018(1):482-492. 3. Piel FB, Steinberg MH, Rees DC. Sickle cell disease. N Engl J Med. 2017;376(16):1561-1573. 4. Rees DC, Williams TN, Gladwin MT. Sickle-cell disease. Lancet. 2010;376(9757):2018-2031. 5. Saraf SL, Molokie RE, Nouraie M, et al. Differences in the clinical and genotypic presentation of sickle cell disease around the world. Paediatr Respir Rev. 2014;15(1):4-12. 6. Hassell KL. Population estimates of sickle cell disease in the U.S. Am J Prev Med. 2010;38(4 Suppl):S512-S521.
