Different types of SCD are more common in specific parts of the world

Genotype Percentage of SCD population Percentage of affected ethnicities
HbSS (sickle cell anaemia)1,2


~70% of patients of African descent
HbSC1,2 ~18%–24%* ~25%–30% of patients of African descent
HbSβ0-thalassaemia1,2 ~1%–6%* Most prevalent in people of Eastern Mediterranean or Indian descent
HbSβ+-thalassaemia1,2 ~1%–6%* Most prevalent in people of Eastern Mediterranean or Indian descent
HbSD1 N/A Most prevalent in people of Northern Indian descent
HbSα-thalassaemia1,3,4 N/A ~30% of patients of African descent

~50% of patients of Middle Eastern or Indian descent
HbAS (sickle cell trait)3,5 Should not be classified as a true form of SCD ~8% of African Americans are carriers of the sickle cell trait



SCD is one of the most common monogenic disorders worldwide4

The prevalence of SCD varies from region to region, and migration is changing the global picture of this disease.2,4–8

world map

By 2050, the number of people born with SCD is expected to grow by 30% around the world9


*Based on 3 large multicentre cohorts of patients with SCD of predominantly African descent in the Americas and the United Kingdom.

Abbreviations: HbA, normal adult haemoglobin; HbS, sickle haemaglobin; SCD, sickle cell disease.


  1. Rees DC, et alLancet. 2010;376(9757):2018–2031.
  2. Saraf SL, et alPaediatr Respir Rev. 2014;15(1):4–12.
  3. Steinberg MH. In: Goldman L, Ausiello D, eds,Cecil Medicine, 23rd ed. Philadelphia, PA; Saunders Elsevier; 2008:1217–1226.
  4. Piel FB, et alN Engl J Med. 2017;376(16):1561–1573.
  5. Centers for Disease Control and Prevention. Data & Statistics: Sickle Cell Disease. www.cdc.gov/ncbddd/sicklecell/data.html. Accessed March 2021.
  6. European Medicines Agency. Orphan designation: EU/3/18/2125. Available at: https://www.ema.europa.eu/en/medicines/human/orphan-designations/eu3182125. Date accessed: March 2021.
  7. Aliyu ZY, et alAm J Hematol. 2008;83:63–70.
  8. Huttle A, et alPediatr Blood Cancer. 2015; 62(7):1131–1136.
  9. Piel FB, et alPLoS One. 2013;10(7):1–14.
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UK | April 2021 | 104288

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