An international group of researchers led by Rutgers has identified 36 genes associated with the risk of developing obsessive-compulsive disorder (OCD) and chronic tic disorders. This study, published in the journal Nature Neuroscience, helps explain why these conditions may occur simultaneously.
To achieve these results, scientists analyzed the DNA of nearly four thousand individuals diagnosed with OCD, tic disorders, or both. The findings also point to genetic links with autism and schizophrenia.
Previously, scientists had identified only a small number of genes individually linked to OCD or chronic tics; the new work significantly expands this list. The study fundamentally increases the catalog of common risk genes, reveals biological connections to autism and schizophrenia, and highlights brain circuits that control impulses, movement, and habit formation.
Gary Hyman, a professor in the Rutgers Department of Genetics and senior co-author of the study, noted in his commentary that understanding these networks in the future could contribute to the development of drugs that target the biological mechanisms of the disorders, rather than just their symptoms.
OCD is characterized by persistent intrusive thoughts and repetitive behaviors, whereas in chronic tics, such as Tourette syndrome, movements or vocalizations occur suddenly and repeatedly, often without the person's ability to control them.
The team focused on rare mutations capable of disrupting the function of important genes responsible for brain development and function. Since many of the 36 genes are associated with both conditions, this may help explain the frequency of simultaneous occurrence of OCD and tic disorders in one person or family members.
Jay Tischfield, Professor Emeritus of the Rutgers Department of Genetics and senior co-author, drew attention to another consequence of the discovery: 'Now you have over 30 targets, and this opens up new possibilities for developing treatments.'
Key findings include: genetic activity analysis showed that many identified genes are active in areas such as the cortex and basal ganglia. These areas are involved in movement, decision-making, and habit formation.
The study combined data from over 30 groups from the USA, Canada, Europe, South Korea, and South America. Whole-exome sequencing was used, a method that studies gene segments responsible for protein production instructions. In some cases, scientists found mutations present in a child but absent in the parents, which helped pinpoint genes potentially involved in the development of the disorders.
Some samples used in the study were collected about 20 years ago and stored in the Rutgers repository because modern sequencing technologies were not yet available at that time. According to Hyman, the participation of families was crucial for using this material now. Analyzing these old samples alongside modern genetic tools allowed for the collection of sufficient data to search for rare mutations and deepen the study of the biological origins of OCD and chronic tic disorders.