How One Child’s Sickle Cell Mutation Saved The Lives Of Many

A millennium ago, a very special child was born in the sub-Saharan desert. A genetic mutation had altered the child’s haemoglobin – the molecules within red blood cells that carry oxygen to all parts of our body. However, it was not harmful because the child only had one copy of the mutation. As nights turn to days and months into years, the child survived. 

This mutation also originated from other 4 independent mutational events – 3 in Africa and the 4th in Saudi Arabia or central India.

Generation after generation, the mutation endures, and for a good reason. People who carried this mutated gene were protected from one of the biggest threats to humans: Malaria. 

Wherever people suffered from Malaria, the protective gene thrived but brought sickle cell along with it. 

Scientists attribute this mutation to evolutionary changes. For most of history, we lived without antimalarial drugs and yet our bodies miraculously fought against this deadly infection. You see the only way we could ever win this battle is if our bodies was less accommodating to the virus. That is exactly the case with the sickle cell, the virus does not thrive on it. 

In 1954, a South African-born geneticist, Anthony C. Allison made an observation in Uganda about the sickle cell mutation. He observed that people in Uganda who have the mutation suffered fewer malaria infections than people with normal haemoglobin.

Later research confirmed Dr. Allison’s finding. The sickle cell mutation seemed to defend against malaria by starving the single-celled parasite that causes the disease. 

The parasite feeds on haemoglobin. Hence, it’s possible that it can’t grow on the sickle cell version of the molecule.

Although sickle cell anaemia still proves to be a heavy public health burden, scientists may have zeroed down on the elusive reason behind sickle cells protective capabilities. 

But there was just one tiny problem – what happens when two descendants of the first person who developed sickle cell anemia, had a family together? Their offspring would inherit two copies of the mutant gene instead of one, causing their blood cells to become defective. Subsequently, these crescent-shaped blood cells would end up clogging their blood vessels. 

The condition would later be named as sickle cell disease – its name attributes the shape of the defective blood cells. Symptoms range from fatigue and anaemia to kidney failure. In early times, the life expectancy of a child suffering from sickle cell disease would only be up to 5 years old. Now some 250 generations later the life expectancy is at 60-68 years old. 

Symptoms Sickle Cell Anaemia: 

• Anaemia & Fatigue – due to lack of oxygen as a result of sickle celled red blood cell.
• Pain occurs due to the blockage of sickle cells in the blood vessels. Pain is episodic and can vary in intensity and period.
• Painful swelling in hands and feet caused by the obstruction in blood flow by the sickle cells
• Repeated frequent infections as the sickle cells damage the spleen
• Delayed growth from infancy due to deficient blood oxygenation
• Eye problems may arise from damage to the low blood circulation to retina

Treatment

The only potential cure is a bone marrow transplant usually for people not older than 16 years due to the high risks which increase with age. This procedure has a high risk of death and finding a suitable donor is very difficult. 

As a result, treatment for sickle cell anemia is usually for symptomatic relief and preventing complications. 

Conclusion

While sickle cell is thought to predominantly affect those of African descent, this mutation was also found in Portuguese, Spanish,  French Corsicans, Sardinians, Sicilians, mainland Italians, Greeks, Turks, and Cypriots.

The severity of sickle cell disease is reduced for those fortunate to have increased levels of fetal haemoglobin persisting into adulthood. Amazingly, to help defend people with sickle cell disease from the severe consequences of this condition, an otherwise silent genetic condition – hereditary persistence of fetal haemoglobin – has arisen in populations where sickle cell disease is common!

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Tags

• genetic disease
• genetics