Gene therapy cures ten “bubble babies” – KIJK Magazine

A rare genetic disease that leaves babies without a functioning immune system from birth has been cured using experimental gene therapy.

The medical world knows about seven to eight thousand genetic disorders (rarely that rare) and paper gene therapy can treat many of them. This has also been shown in practice for some diseases, including beta thalassemia and haemophilia B. Children with the congenital malformation SCID can now benefit from gene therapy. A new study published in The New England Journal of Medicinereports the first 10 children to undergo gene therapy who are now all healthy and leading normal lives.

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Why gene therapy?

Our body is made up of about 100,000 billion cells that together ensure that everything works properly. To do this, they need protein. If you imagine a cell as a factory, proteins are the factor that keeps that factory running. They know what to do because they have a clue at their disposal that can be found in the cell nucleus: our DNA.

The genes that make up our DNA tell us exactly what is expected of proteins. Then there is also such a thing as RNA. Think of it as a medium: RNA is a copy of a piece of DNA that is used as the blueprint for building a protein. But sometimes there is something wrong with one or more genes. And if the directory is wrong, an execution error will also occur. In this case you are talking about a genetic disorder. Gene therapy can correct these errors.

bubble boy

SCID stands for severe combined immunodeficiency and is caused by a DNA error in blood stem cells. Patients with this condition do not produce certain types of immune cells, which means that the body cannot defend itself against pathogens. A cold virus that is fairly harmless to us can be fatal to children with SCID.

For years, the only treatment that could keep children with ADHD alive for more than a few months was to put patients in some kind of sterile air incubator. Hence the nickname “bubble babies”. The most famous example is 12-year-old David “Bubble Boy” Vetter. He was also able to get out, thanks to a suit developed by NASA (see image at the top of this article).

correcting the mistake

After a few years, bone marrow transplantation has resulted in a large number of cured patients, but the disadvantage of this is that a suitable donor is not always available. Furthermore, transplantation carries the necessary risks, including an increased risk of leukemia. So Stock quickly turned to gene therapy. It can correct the DNA error in blood stem cells and thus cure the disease.

Leiden University Medical Center (LUMC) achieved success in this area earlier this year. A team of doctors treated a baby with SCID – called RAG1-SCID – who was just a few months old. “The baby has gone through the treatment without any problems and the immune system is responding well to the usual newborn vaccinations,” Arjan Lancaster, a professor of pediatrics and stem cell transplantation, said at the time.

vaccination

In the new study, ten children with Artemis-SCID — a rare form of SCID — underwent gene therapy. The researchers extracted stem cells from the patients’ bone marrow. A good copy of the broken gene was then built into the DNA of these cells with the help of an inactivated virus. Those repaired stem cells were given back to the patients.

More than two years after the first treatment, all 10 children are healthy and leading normal lives. The doctors were able to safely stop all ongoing treatments and administer childhood vaccinations.

Low dose chemotherapy

Frank Stahl, professor of molecular stem cell biology at LUMC, was impressed by this finding. “This is a real breakthrough for this very rare disease. But what makes the study particularly impressive is that the researchers used a low dose of chemotherapy, a quarter of what they normally use.”

Before the new corrected stem cells were given back to the children, they first had to undergo chemotherapy. Staal: “In this way, space is made in the bone marrow for new cells and old cells (which contain the genetic error, ed.) are cleared.”

However, this chemotherapy causes DNA damage, and the Artemis gene is needed to repair the DNA damage. That was the tricky part about this study: determining exactly the right dose of chemotherapy for each child, while making enough space in the bone marrow for the corrected stem cells without causing too much collateral damage. The researchers succeeded in doing this in these 10 patients. This is hopeful and the results also look promising in the long term.”

Sources: New England Journal of Medicine, LUMC, New Atlas

Photo: Universal History Archive/Getty Images

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