A groundbreaking study explains how Huntington’s mutation remains harmless for years before causing severe symptoms
Washington: Scientists are making strides in understanding Huntington’s disease, a hereditary condition that can be devastating. It usually hits people in their prime, causing nerve cells in the brain to deteriorate.
While the genetic mutation has been known for a while, the mystery was why some folks with the mutation don’t show symptoms until later in life. New research shows that this mutation can sit quietly for decades before it becomes harmful.
It turns out the mutation is harmless for a long time, but eventually, it grows and triggers toxic proteins that kill brain cells. Dr. Mark Mehler, who leads a brain disorders institute, called this research a “landmark” study that answers many questions in the field.
As brain cells die, people start facing issues with movement, thinking, and behavior. Symptoms like involuntary movements and personality changes usually kick in between ages 30 and 50, worsening over 10 to 25 years.
The research team from the Broad Institute, McLean Hospital, and Harvard Medical School analyzed brain tissue from 53 Huntington’s patients and 50 healthy individuals. They looked at half a million cells to understand the mutation better.
They focused on a specific DNA sequence that repeats itself. In Huntington’s patients, this sequence is repeated at least 40 times, while in healthy individuals, it’s only 15 to 35 times. They found that these repeats can expand over time, and once they hit around 150 repeats, brain cells start to suffer.
Steve McCarroll, one of the study’s authors, said the findings were surprising. The study, published in the journal Cell, was partly funded by the Howard Hughes Medical Institute.
The researchers noted that these DNA repeats grow slowly in the first two decades of life, but the pace picks up dramatically once they reach about 80 repeats. The longer the repeats, the earlier symptoms can appear.
Some scientists were skeptical at first, but McCarroll clarified that while fewer than 100 repeats aren’t enough to cause the disease, having at least 150 is a different story.
Researchers are hopeful that these insights could lead to ways to delay or even prevent Huntington’s, which affects around 41,000 Americans. Currently, treatments focus on managing symptoms.
Experimental drugs aimed at reducing the harmful protein from the mutated gene have faced challenges in trials. The new findings suggest that this might be because only a few cells have the toxic protein at any given time.
Researchers believe that slowing down the expansion of these DNA repeats could be a more effective approach. While there are no guarantees, McCarroll mentioned that many companies are starting or expanding efforts to tackle this issue.
