Gene therapy proves successful in treating sickle cell disease

A young boy in France has been cured of sickle cell disease by gene therapy, reveals a study that proves promising in offering a cure to this devastating disease.

Sickle cell disease (SCD) is a group of highly devastating hereditary conditions that affect over 3 million people worldwide, with over 270,000 infants born with the disease each year. It is caused by the production of abnormally shaped red blood cells, due to a single mutation in the ╬▓globulin gene.

A normal red blood cell is shaped like a disc, and one of its main functions is to carry oxygen throughout the body. In SCD, the cells are less able to carry oxygen, which causes them to have a sickle-like structure due to low tension.  The cells are also less elastic than normal, which limits their ability to deform to pass through capillaries.

These red blood cell deformities cause many symptoms, including a lack of oxygen in the body causing anaemia, an increased risk for infections and what are known as sickle cell crises. These are due to the blood vessels becoming blocked by the deformed cells, restricting the blood flow.

Currently, the only cure for SCD is a bone marrow transplant, but only 10% of people find a perfectly matching donor, and this is a procedure that carries many risks, so is not used very often. Treatments are therefore aimed more towards the management of the disease, such as treating pain, anaemia, and preventing infections. Patients sometimes need blood transfusions every couple of days.

However, a group of scientists in Paris have successfully cured a teenager of sickle cell disease by a method called gene therapy. The team, led by Professor Marina Cavazzana, used a viral vector to insert a functioning gene into the bone marrow where red blood cells are created, to ensure the formation of healthy cells.

In their paper, the scientists explain that 15 months after the treatment the boy appears to be cured of the disease; he no longer suffers from painful episodes of sickle cell crises, and has stopped using opioid pain killers. This is the first case where gene therapy has been successful in curing the disease, but many more will need to follow in order for this process to be considered a cure.

Unfortunately, gene therapy is expensive and would therefore only be accessible to people in more developed countries, whereas the highest incidence of SCD is in Africa, Asia and other poorly developed countries. There is therefore a lot of work to be done in order to make gene therapy an accessible treatment to all.

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