Why Huntington’s disease may take so long to develop

Repeated bits of the disease-causing gene pile up in some brain cells

This image shows an MRI scan of the brain of someone with Huntington's disease.

Huntington’s disease causes certain brain regions to die, as indicated by the darker areas in the center of this MRI image of the brain of a 21-year-old with the disease. Researchers have discovered that adding extra DNA to the gene that causes the disease leads to brain cell death.