Lethal Advantage12th July 2006
Coinciding with sickle cell awareness week at the beginning of June, the BBC screened Sickle Cell Disease: A Lethal Advantage. Tracing the history of the disease, epidemiologists uncovered some interesting findings which have promoted the high incidence of sickle cell trait in certain black populations.
Sickle cells form when red blood cells give out oxygen and combine into a rigid sickle cell shape which prevents the cells from flowing around the blood stream, often resulting in agonising, burning pains among other symptoms. The disease has been prevalent in black populations for centuries yet, although Africans had been in the USA for 400 years, the disease was only discovered and formally identifed when a West Indian student in Chicago presented with a strange blood disorder at the turn of the last century; it subsequently took 50 years to fully understand the disease which is an inherited condition resulting from specific genetic markers.
Children with sickle cell disease will have two parents with sickle cell trait (ie the genetic markers which combine to create the condition in offspring). There is a 25% chance that a child with both parents having sickle cell trait will be born with the disease. Normally, natural selection would gradually cause such a condition to gradually phase out but epidemiologists found that certain populations in the African and Asian subcontinents had a much higher prevalence of sickle cell trait than would normally be expected.
Studies subsequently confirmed that the proportion of the population with sickle cell trait was much higher where there was a high incidence of malaria. Somehow, people with sickle cell trait had a higher immunity to malaria than those with normal or sickle cells and over the years the balance of the population with the trait gradually increased as the rest of the population succumbed to malarial disease.
Today, it is estimated that a quarter of a million people each year are born with sickle cell disease. Though incurable, the condition can be managed with a combination of drug and lifestyle therapies.
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Title: Lethal Advantage
Author: Chris May
Article Id: 524
Date Added: 12th Jul 2006