Probability of Being a Sickle Cell Trait Carrier

Sickle cell trait (carrying one copy of the sickle cell gene) affects approximately 8% of Black Americans, or about 3 million people. Sickle cell disease (inheriting two copies, one from each parent) affects approximately 1 in 365 Black births and about 1 in 16,300 Hispanic births. An estimated 100,000 Americans live with sickle cell disease.

Sickle cell trait generally does not cause symptoms, though carriers may experience complications under extreme conditions (extreme dehydration, high altitude, intense physical exertion). When two carriers have a child together, there is a 25% chance the child will have sickle cell disease, a 50% chance of carrying the trait, and a 25% chance of inheriting neither.

Sickle cell disease causes significant morbidity, including pain crises, anemia, organ damage, stroke risk, and reduced life expectancy (median survival about 43-54 years). Treatment has improved with hydroxyurea, blood transfusions, and pain management. Gene therapy (Casgevy, using CRISPR gene editing) was FDA-approved in 2023 as the first gene therapy for sickle cell disease, offering a potential functional cure for some patients.