Although they’re meant to correct genetic mistakes, when faced with long repetitive CAG stretches, DNA repair proteins can mistakenly cause them to grow even longer. Through this cumulative knowledge, a starting lineup has emerged of key DNA repair proteins most implicated in HD. These structures are loops of DNA that can be detected by the DNA repair proteins in our cells. So, who exactly are the Messis and Ronaldos of the HD DNA repair team? Like referees on the pitch, researchers carefully tested what happened when each protein joined or left the DNA expansion lineup.