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Individuals are diagnosed with sickle cell disease (SCD) if they have one of several genotypes that result in at least half of their hemoglobin (Hgb) being Hgb S. Sickle cell anemia (SCA) refers to the condition associated with homozygosity for the Hgb S mutation (Hgb SS). Other Hgb mutations may occur with Hgb S causing a similar but milder condition. In SCA, the presence of intracellular hemoglobin S polymerization leads to chronic hemolytic anemia, vasoocclusive crises of varying severity and frequency with cumulative organ damage and systemic manifestations that include impairment in growth and development, susceptibility to infection, and reduced quality and duration of life


Segal JB et al. Hydroxyurea for the Treatment of Sickle Cell Disease. Rockville, MD: Agency for Healthcare Research and Quality, 2008 Feb. Report No. 08-E007



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Worldwide (SCD): Millions
United States (SCD): ~1 in 500 African American births (~72,000)
1 in 1000–1400 Hispanic babies each year
United States (Sickle cell trait): 1 in 12 African Americans (~2 million people)
U.S. median life expectancy for Hgb SS/SC males 42 years/60 years
U.S. median life expectancy for Hgb SS/SC females 48 years/68 years

Mortality reductions have been attributed to several factors: development of sickle cell treatment programs, increased clinical research in sickle cell disease (SCD), and establishment of newborn screening programs coupled with penicillin prophylaxis

Platt OS et al. N Engl J Med 1994;330:1639–1644 (3764 patients. followed to determine life expectancy)

Sickle Cell Research for Treatment and Cure. Bethesda, MD: NIH Publication No. 02-5214;2002:1–16

Dept. of Energy, Human Genome Project. [accessed August 5, 2013]


Major Sickle Hemoglobinopathies: Laboratory Features

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Major Sickle Hemoglobinopathies: Laboratory Features
Disorder Common Hematologic Findings in Adults
Percent MCV(fL) Hgb (g/dL) Percent of Hemoglobin
Hgb A/A2 Hgb F Hgb S
SCD-SS 65 80–100 6–10 0/2–3 2–15 >85
SCD-SC 25 75–90 10–12 0/0 1–7 50
SCD-S β+ thalassemia 8 65–75 8–12 5–30/3–6 2–10 70–90
SCD-S β-thalassemia 2 65–85 6–10 0/4–6 2–15 >85
SCD-S δβ thalassemia <1 60–80 10–12 0/N-low 10–15 >80
S-HPFH pancellular <1 80–90 12–13§ 0/1–3 20–30 >70


Approximate percent of U.S. patients determined by neonatal screening

50% Hgb C

Hgb A2 normal to low

§Hct 38–40%


Adams JG 3rd. Clinical laboratory diagnosis. In: Embury SH et al., eds. Sickle Cell Disease: Basic Principles and Clinical Practice. New York, NY: Raven Press; 1994:457–468

Bunn HF, Forget BG. Sickle cell disease—clinical and epidemiologic aspects. In: Hemoglobin: Molecular, Genetic and Clinical Aspects. Philadelphia, PA: WB Saunders; 1986:502–564

Glader BE. Anemia. In: Embury SH et al., eds. Sickle Cell Disease: Basic Principles and Clinical Practice. New York, NY: Raven Press; 1994:545–554

Kinney TR et al. Br J Haematol 1978;38:15–22

Murray N et al. Br J Haematol 1988;69:89–92

The Management of Sickle Cell Disease, ...

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