By sequencing the genomes of people with obsessive-compulsive disorder and members of their families, a team of Shanghai Jiao Tong University scientists has uncovered mutations that implicate chromatin modifications in the condition. Building off of previous exome-sequencing studies for OCD, the researchers performed whole-genome sequencing on 53 parent-offspring families with offspring affected with OCD to investigate all rare de novo variants and insertions/deletions. They found strong evidence for a high occurrence of mutation at promoter-interacting loops and observed that de novo mutations preferentially occurred on intolerant genes and affected genes regulating chromatin modification. As reported in Science Advances, the investigators identify three high-confidence chromatin modifiers as OCD candidate risk genes.