This year has been full of good news stories about gene-replacement therapies alleviating severe genetic disorders in children, suggesting they are finally living up to their promise after a bumpy few decades.
鈥淲e鈥檙e curing kids of fatal diseases. It鈥檚 wonderful,鈥� 聽at the University of California, Los Angeles told 快猫短视频 in May after successfully using a gene-replacement therapy to reverse a rare life-threatening immune condition called leukocyte adhesion deficiency in nine children.
Gene-replacement therapies are used to correct genetic disorders that are caused by mutations in a single gene that stop it from working properly. They involve inserting new, working copies of the gene into relevant cells, typically using a virus as a carrier.
Advertisement
The approach created a stir in the 1990s after alleviating an immune disorder called severe combined immunodeficiency in several children. However, it fell out of favour in the early 2000s after causing leukaemia in some of these children.
Since then, scientists have been trying to make gene-replacement therapies safer, mainly by modifying the viruses that deliver them to prevent off-target effects.
Several of these newer therapies have been approved for commercial use by medical regulators this year and others have shown impressive results in clinical trials.
One called Upstaza, for instance, was for treating a rare, fatal movement disorder called AADC deficiency that is caused by a defective DDC gene. The therapy involves injecting new, working copies of the DDC gene into the brain.
One child who received the therapy in a clinical trial went from having zero movement, head control or speech to being able to run, jump, ride horses and speak in multiple languages. 鈥淚t鈥檚 a dream come true,鈥� her father told 快猫短视频.
Three other gene-replacement therapies were approved by the US Food and Drug Administration (FDA) this year: one for a , one for , and another for a . The agency has only approved two other gene-replacement therapies previously: for an inherited form of vision loss in 2017 and for spinal muscular atrophy in 2019.
More should follow on the back of positive clinical trial results reported this year for gene therapies for severe combined immunodeficiency, recessive dystrophic epidermolysis bullosa, a painful skin condition, and infantile GM1 gangliosidosis and , both childhood neurodegenerative disorders.
Some of these trials have been running for more than five years and no major safety concerns have arisen so far, but the participants will be monitored for at least 15 years for any adverse effects, which is a requirement of the FDA for all gene therapies.
鈥淭here is a theoretical risk that newer gene therapies could cause cancer down the track, but most are for severe, devastating diseases that don鈥檛 have good treatments so the benefits are often seen as outweighing the risks,鈥� says at the University of Sydney in Australia.
Gene-replacement therapies are also being developed for a range of other single-gene disorders like , and .
There are more than 10,000 known single-gene disorders in total and most have the potential to be corrected using gene-replacement therapies, says Ginn.
Sign up to our free Health Check newsletter that gives you the health, diet and fitness news you can trust, every Saturday
