Incidence and Inheritance


  • 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

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