Scientists uncover why some Huntington's disease patients decline years earlier

A new study published in the journal Neuron has discovered why some individuals with Huntington's disease experience onset of symptoms and progression of the disease at a much earlier age than others. The research led by Dr. Michael Hayden of the University of British Columbia reveals how a specific genetic variant accelerates the development of Huntington's disease by triggering excessive DNA alterations in the brain's most susceptible neurons.

The study explains that individuals carrying this particular genetic variant have a more rapid acceleration of the disease, but the underlying reasons were previously unknown. Dr. Hayden emphasized that this study provides a clear answer to this question and highlights that repeated expansion of the mutation plays a significant role in Huntington's disease and could serve as a potential treatment target.

Huntington's disease is a rare inherited neurological disorder causing the progressive destruction of nerve cells in the brain, leading to issues with movement, cognition, and emotional well-being. There is currently no cure or treatment to slow down its progression.

The researchers compared neurons that died in patients with Huntington's disease to those in healthy individuals and found that the brain cells in those with the disease showed markedly higher expansion of the genetic mutation. Dr. Hayden stated, "When we looked at the neurons that are dying in Huntington's disease, we saw much greater expansion of the genetic mutation."

This extensive research also indicates that a small proportion of people with Huntington's disease have this genetic variant and develop the disease earlier than others. However, until now, the reason why this seemingly minor DNA change results in such a dramatic effect on disease onset and progression remained a mystery.

The study identified a key clue to understanding this phenomenon. While the mutation exists throughout the body, the expansion process appears to be highly localized in specific brain cells. Blood tests, on the other hand, showed little evidence of the significant changes occurring within the brain's neurons.

The research suggests that this mutational expansion is selectively concentrated in the brain, which may explain why Huntington's disease, despite the mutation being present in every cell, is fundamentally a brain disease. The findings imply that blood tests may not accurately reflect the progression of the disease in the brain, which is crucial information for future Huntington's disease research and clinical trials.

While other factors likely contribute to the loss of neurons in Huntington's disease, the study provides compelling human evidence that the expansion of the Huntington mutation is a crucial factor in disease progression. Dr. Hayden concluded that suppressing this expansion could potentially delay the onset or progression of the disease, opening up new therapeutic avenues. Further research is required to validate these findings and develop effective treatments.