When someone with Huntington’s disease experiences new symptoms, is HD always the cause? Not necessarily. A new review explores catatonia, an uncommon condition that can cause changes that overlap with HD symptoms.

Scientists discovered a pocket on a protein called MSH3 that helps it grab DNA containing CAG repeats. By blocking this interaction, they slowed the growth of CAG repeats in cells, without removing the protein entirely.

A change in one gene can disrupt thousands of others in HD. A study in pigs suggests an explanation: expanded huntingtin interferes with chemical marks on DNA. The same effect wasn’t seen in mice, showing that the animal model matters.