What is the prevalence of hemoglobinopathy retinopathy?

Updated: Sep 03, 2019
  • Author: Brian A Phillpotts, MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Answer

United States

About 10% of African Americans have an abnormal hemoglobin gene. About 8% of African Americans are heterozygous for Hb S. In the United States, sickle cell anemia primarily occurs in the black population, with approximately 0.2% of African American children afflicted by this disease. The prevalence in adults is lower because of the decrease in life expectancy.

Sickle cell anemia is a homozygous-recessive disorder, that is, the individual receives 2 mutant genes that code for the variant beta globin chain. Sickle cell anemia is most common where the Hb S gene is inherited from both parents, each of whom is a healthy carrier of the gene (Hb AS).

Sickle cell C disease is the second most common form. The hemoglobinopathy results from inheriting 1 Hb S gene and 1 Hb C gene, which is common in West African populations.

Sickle cell-thalassemia disease is the third most common hemoglobinopathy.

Different genes within a population determine the frequency of sickle cell disease at birth. The inheritance pattern for hemoglobinopathies is autosomal-recessive (a mendelian pattern). If each parent carries 1 Hb S gene, a 25% chance exists for offspring to have sickle cell disease, a 50% chance for them to have the carrier state, and a 25% chance for them to have normal hemoglobin. The frequency for passing the mutated gene is the same for each pregnancy, regardless of the outcome of the previous pregnancy. With each pregnancy, a 75% chance exists that the newborn will not have sickle cell anemia.

International

See Race.


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