Incidence and Inheritance

Incidence

• Sickle cell disease is one of the most common genetic diseases in the United States
• It affects more than 50,000 Americans, mainly those of African descent. It also affects those of Mediterranean, Caribbean, South and Central American, Arabian or East Indian heritage
• About one out of every 375 African-American children is affected by sickle cell disease

Inheritance

• Sickle cell disease and other sickling hemoglobin disorders are inherited in an autosomal recessive pattern
• The parents of a child with a Sickle hemoglobinopathy are healthy carriers of the disease and have one normal gene and one abnormal gene



• With each pregnancy, carrier parents have a 25% chance of having a child with two copies of the abnormal gene, resulting in a sickle hemoglobinopathy
• Carrier parents have a 50% chance of having a child who is an unaffected carrier
• These parents also have a 25% chance of having an unaffected, non-carrier child
• These risks hold true for each pregnancy
• Sickle cell disease occurs when one gene for production of Hb S is inherited from each parent
• Other sickling diseases occur when the child inherits a gene for Hb S from one parent and a gene for another abnormal form of hemoglobin (Hb C, Hb E or a thalassemia) from the other parent

                                                                              << Previous  Next >>