Huntington’s disease and Friedreich’s ataxia are two debilitating diseases that progress to damage the nervous system and the brain over time. They are caused by parts of your DNA repeating themselves over and over again — kind of like a stuck record that gets worse the longer it plays.

Now scientists have found a way to sort those repetitive bits with a new type of gene-editing tool called base editing, rewriting single letters at a time in the DNA without cutting the entire strand.

Two types of base editors were used: cytosine and adenine.

The researchers tested the tools on mice and on cells of patients with Huntington’s or Friedreich’s ataxia and found that by changing just a few letters within the repeated DNA sections, they became more stable — preventing growth and ultimately more damage.

In mice, the brain remained more stable, and the worsening symptoms slowed.

While in its early stages, the research opens the door to potential treatments that don’t just mask symptoms — but could potentially tackle the disease at the fundamental level.

The article was published in Nature Genetics.

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