Sickle cell disease is passed on genetically by carriers or people with the “trait” (those who carry only one sickle cell gene along with one normal gene and typically do not have any manifestations of the disease other than mild anemia). If both parents carry the gene, there is a 25% chance per pregnancy of having a child with sickle cell disease and a 50% chance of passing the gene on to their children.
In the US, about 90,000 to 100,000 people have the disease and about one in 12 African-Americans carry the trait. In other parts of the world (Sub-Saharan Africa, the Middle East, South America, Caribbean Islands, and India), the prevalence is much more, with millions of people being affected.