👩‍⚕️ Huntington's disease has been successfully treated for the first time

• A gene therapy has for the first time been shown to slow Huntington's disease by 75 percent after three years in a clinical trial.
• The treatment lowers the levels of the harmful huntingtin protein by injecting a modified virus directly into the brain.
• The results provide proof that the disease can be treated, opening possibilities for other neurodegenerative conditions as well.

In September 2024, the American biotech company UniQure presented results from an international clinical trial. For the first time, a treatment has been shown to slow Huntington's disease. The gene therapy reduced disease progression by 75 percent after three years in a small group of patients.

The announcement came as a surprise to almost everyone involved. Even the researchers who had worked on the study only learned the results when UniQure sent out a press release. This is because such results are kept secret to avoid accusations of insider trading.

A hereditary disease without previous treatment

Huntington's disease is caused by a single faulty gene and progressively kills cells in specific areas of the brain. It leads to dementia, incapacity and ultimately death. The first symptoms usually appear in a person's thirties or forties and include mood swings, anger and depression.

As the disease progresses, patients develop uncontrollable jerky movements, cognitive decline and personality changes. They eventually lose the ability to live independently. Many die within two decades of diagnosis.

Because the disease is hereditary, anyone with an affected parent has a 50 percent chance of developing it. Approximately 75,000 people have Huntington's disease in the UK, US and Europe. Many more carry the faulty gene.

The gene that causes the disease was identified as early as 1993. But despite over three decades of research, no treatment has been able to affect the disease's progression. Until now.

The first treatment that actually works

The treatment is far from simple. A surgical team in Cardiff spent years building the only clinic in the UK with the capacity to perform the procedure. It is also one of only a few worldwide.

The operation involves injecting a genetically modified virus directly into the brain. The procedure lasts twelve to fourteen hours and is carried out inside an MRI scanner. The virus then spreads through the brain cells and lowers the levels of the mutated huntingtin protein.

All humans have two copies of the Huntington gene. Those who have the disease have one normal copy and one mutated copy. The mutated copy produces a variant of the huntingtin protein that is slightly toxic to the body's cells. The cells can handle this toxicity up to a certain point. That is why the disease begins in middle age and not in infancy. But eventually the cells begin to fail.

The treatment is essentially a small piece of DNA that lowers the levels of the huntingtin protein in the brain. This allows the cells to recover and begin functioning better. The DNA activates neurons to produce a therapeutic molecule that intercepts and neutralizes the RNA carrying instructions for making the faulty protein.

Decades of research behind the results

The first successful treatment did not come out of nowhere. A large observational study called Enroll-HD has collected data over two decades from more than 30,000 patients. The study has been funded by the CHDI Foundation, an American non-profit organization. It has helped researchers understand the disease better and learn how to conduct effective clinical trials.

The patients who voluntarily underwent the experimental treatment took a significant risk. Once the treatment has been placed in the brain, it cannot be removed. Participants knew that the treatment might not work and that it could also cause harm. Despite this, they chose to participate. Many of them have children or nieces and nephews who are at risk of developing the disease.

Next steps and other treatments

The treatment is delivered in a single surgical procedure. It will likely be expensive. Previous gene therapies have cost more than one million pounds per patient.

In November 2025, the US Food and Drug Administration announced that it needs to see more evidence that the treatment works before it can be approved. UniQure's stock price fell by 66 percent following the announcement. The company states that they are continuing to work with the FDA to find a path forward.

UniQure's treatment is not the only one that has shown positive signals. Other studies are investigating alternative methods for lowering the huntingtin protein. Additional research is looking at entirely different approaches. One example is the drug pridopidine in tablet form, which stimulates a molecule on the cell surface.

Researchers also see possibilities for other diseases. Solutions being developed for Huntington's disease may be applicable to other conditions that share some of the underlying mechanisms. This includes diseases such as myotonic dystrophy or certain forms of motor neurone disease.

The UniQure study has shown that it is possible to slow the deterioration in Huntington's disease by lowering huntingtin levels. It is the first time a treatment has been shown to affect this disease.

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