Sickle Cell: A Unique Evolution | Black History Month 2023

In Sub-Saharan Africa, South America, the Caribbean, Central America, South-East Asia and parts of the Mediterranean and Middle East, many people share one tiny thing in common: a genetic mutation known as the sickle cell gene. Inheriting one gene causes the Sickle Cell Trait (SCT) and because this provides protection against the malaria parasite, the disease of sickle has evolved in these areas due to the high prevalence of the malaria parasite disease-carrying mosquitoes.

The sickle cell gene is recessive and a single gene has no ill effect on a person. However, when two carriers have a baby and that baby gets two sickle cell genes, a condition called homozygous state, that baby will develop sickle cell disease (SCD).

Sickle cell disease (SCD) is a genetic disorder of hemoglobin that results in red blood cells changing shape, going from round to a sickled shape. This sickling phenomenon can have dramatic results, including blood flow issues (called sludging), damage to your extremities (hands & fingers, toes and feet), infarctions in bones, circulation issues, and respiratory issues. It can appear in many ways, but the most well-known and severe form of SCD is called sickle cell anemia.

This disorder, because of its evolutionary origins, is most prominent in Black patients. In the United States, approximately 1 in 13 Black babies are born with the SCT, and 1 in 365 babies are born with both genes, meaning they will develop SCD.

Diagnoses are usually made during routine newborn blood tests, and it is possible to diagnose the baby in the womb. Manifestations of SCD will start to appear from about 6-9 months and onward, and are immediately treatable. As the disease is inherited due to abnormal genes, it is not possible to spontaneously develop SCD or to catch it from somebody.

Unique conditions like SCD are a clear example of why diversity and inclusivity in medical research is so important. Considering the unique way our evolutionary heritage can impact – or not impact - our health leads to faster, more accurate diagnoses and better outcomes.

Our sincere thanks to Dr. Peter Kagoma for lending his expertise.