Having 35 copies of the CAG triplet in the gene that causes Huntington’s disease is not a problem. Inheriting 40 could be a sign that goes unnoticed for decades, until reaching 80. From there, the process accelerates and neural death occurs when reaching 150 repeats. Huntington’s disease neurodegeneration is not determined by what, but by how much, according to a study conducted at the Broad Institute.