Despite the best efforts of modern medicine, Huntington’s disease is a condition that still comes with a tragic prognosis. Primarily an inherited disease, its main symptoms concern degeneration of the brain, leading to issues with motor control, mood disturbance, with continued degradation eventually proving fatal.Researchers have recently made progress in finding a potential treatment for the disease. A new study has indicated that an innovative genetic therapy could hold promise for slowing the progression of the disease, greatly improving patient outcomes.TreatmentHuntington’s disease stems from a mutation in the huntingtin gene, which is responsible for coding for the huntingtin protein. This gene contains a repeated sequence referred to as a trinucleotide repeat, where the same three DNA bases repeat multiple times. The repeat count varies between individuals, and can change from generation to generation due to genetic mutation. If the number of repeats becomes too long, the gene no longer codes for huntingtin protein, and produces mutant huntingtin protein instead. The mutated protein eventually leads to neural degeneration. This genetic basis is key to the heritability of Huntington’s disease. If one parent carries a faulty gene, their children have a fifty percent chance of inheriting it and eventually developing the disease themselves. Over generations, the number of repeats can increase and lead to symptoms appearing at an earlier age.Excessive repeats in a critical gene are the root cause of Huntington’s disease. Credit: NIST, public domainThe new treatment relies on advanced genetic techniques to slow the disease in its tracks. It involves the use of a custom designed virus, which is inserted into the brain itself in specific key areas. It’s a delicate surgical process that takes anywhere from 12 to 18 hours, using real-time scanning to ensure the viral payload is placed exactly where it needs to go. The virus carries a DNA sequence and delivers it to brain cells, which begin processing the DNA to produce small fragments of genetic material called microRNA. These fragments intercept the messenger RNA that is produced from the body’s own DNA instructions, which is responsible for producing the mutant huntingtin protein which causes the degenerative disease. In this way, mutant huntingtin levels are reduced, drastically slowing the progression of the disease.The effects of the treatment are potentially game changing, with progression of the disease slowed by 75% in study patients. Results indicate that with effective treatment, the decline expected over one year would instead take a full four years. In more qualitative areas, some patients in the trial have managed to maintain the ability to walk at a point when they would typically be expected to require wheel chairs. In typical Huntington’s cases, the onset occurs between 30 to 50 years old, with a life expectancy of just 15 to 20 years after diagnosis. The hope is that by delaying the progression of the disease, affected patients could have a greater quality of life for much longer, without suffering the worst impacts of the condition.A microscopic image of a neuron damaged by mutated Huntingtin (mHtt) protein inclusion, visible via orange stain. Credit: Dr Steven Finkbeiner, CC BY-SA 3.0The initial trial involved just twenty-nine patients, but results were promising. Data indicated consistent benefit to patients three years after the initial surgery. Crucially, the treatment isn’t just slowing symptoms, but there is also evidence it helped to preserve brain tissue. Markers of neuronal death in spinal fluid, which would typically increase as Huntington’s disease progresses, were actually lower than before treatment in study patients.The therapy isn’t without complications. Beyond the complicated and highly invasive brain surgery required to get the virus where it needs to go, some patients developed inflammation from the virus causing some side effects like headaches and confusion. There’s also the expense — advanced gene therapies don’t come cheap. However, on the positive side, it’s believed the treatment could potentially be a one-off matter, as the brain cells that produce the critical microRNA fragments are not replaced regularly like other more disposable cells in the body. While it’s a new and radical treatment, pharmaceutical company UniQure has plans to bring it to market as soon as late 2026 in the US, with the European market to follow.It’s not every day that scientists discover a new viable cure for a disease that has long proven fatal. However, through genetic techniques and a strong understanding of the causative factors of the disease, it appears scientists have made progress in tackling the spectre that is Huntington’s disease. For the many thousands of patients grappling with the disease, and the many descendents who struggle with potentially having inherited the condition, news of a potential treatment is a very good thing indeed.Featured image: “Huntington” by Frank Gaillard.