Spit Samples Uncover Genetic Risk Factors for Pediatric Obsessive-Compulsive Disorder

Summary: Children and young adults with a specific variant of the PTPRD gene are at greater risk of developing obsessive-compulsive disorder.

Source: University of Galgary

Researchers at the University of Calgary and The Hospital for Sick Children (SickKids), in Toronto, have discovered genetic risk factors for OCD that could help pave the way for earlier diagnosis and improved treatment for children and youth.

“Our group made the first finding of a genome-wide significant risk gene relevant to childhood OCD,” says Dr. Paul Arnold, MD, PhD, co-principal investigator, a professor and director of The Mathison Centre for Mental Health Research & Education at the Cumming School of Medicine. “We’ve known that OCD runs in families, but we hadn’t identified and validated specific genetic risks of OCD symptoms in children and youth until now.”

The research drew on the Spit for Science study, a research project led by SickKids looking at how genes interact with the environment to impact physical and mental health.

Participants from the community were recruited via an innovative research design run out of the Ontario Science Centre, which has generated a diverse sample of 23,000 participants thus far. Participants provide a DNA sample through their saliva, do a cognitive task, and complete questionnaires on their health, lifestyle and behaviours.

In this study, saliva samples from over 5,000 children and youth were scanned and compared to participant responses using the Toronto Obsessive-Compulsive Scale (TOCS). The TOCS is a questionnaire used to evaluate obsessive-compulsive traits developed by Dr. Arnold and the team at SickKids.

After looking across millions of genetic variants from the saliva samples, the team identified that children and youth with a genetic variant in the gene PTPRD had a greater risk for more obsessive-compulsive traits.

The findings are published in Translational Psychiatry.

“Discovering the genes involved in OCD is critical to help improve patients’ lives. It is still early days, but our hope is these findings will lead us to understand the causes of OCD, which in turn could help identify people with OCD sooner and develop better treatments,” says Dr. Christie Burton, PhD, lead author and research associate in the Neurosciences & Mental Health program at SickKids.

The research team, which also includes co-principal investigators, Drs. Jennifer Crosbie, PhD, Clinical Psychologist at SickKids, and Russell Schachar, MD, Psychiatrist at SickKids, highlight that a greater understanding of the underlying genetics may eventually be an important complement to clinical assessment and could help guide treatment options in the future.

“OCD can present very differently and at various ages in each individual, adding to the challenge of treatment and diagnosis,” says Crosbie, who is also an associate scientist in the Neurosciences & Mental Health program at SickKids. “Studies like this one are an important step towards developing precision medicine approaches for mental health.”

This shows DNA
After looking across millions of genetic variants from the saliva samples, the team identified that children and youth with a genetic variant in the gene PTPRD had a greater risk for more obsessive-compulsive traits. Image is in the public domain

Sam, 17, lives with OCD and with therapy and medication, he says he has been able to face his obsessions and compulsions, ride out the anxiety and control his actions. Looking back at his childhood, Sam says he had some OCD tendencies as early as elementary school, but neither he nor his family realized he had a mental illness. The researchers hope that by understanding the genetics of OCD they can develop better treatments, improve outcomes and diagnose youth like Sam earlier.

“At first I wasn’t sure what to do with the diagnosis, it was very foreign, I didn’t want to perceive myself as having a mental health issue,” says Sam. “But, knowing I have OCD helped me overcome the challenges. With therapy and medication, I’ve stopped OCD from overtaking my life and taken back control.”

Sam is a real teenager, but Sam isn’t his real name. He says due to the stigma around OCD he would prefer to remain anonymous.

About this genetics and OCD research news

Source: University of Calgary
Contact: Kelly Johnston – University of Calgary
Image: The image is in the public domain

Original Research: Open access.
Genome-wide association study of pediatric obsessive-compulsive traits: shared genetic risk between traits and disorder” by Christie L. Burton, Mathieu Lemire, Bowei Xiao, Elizabeth C. Corfield, Lauren Erdman, Janita Bralten, Geert Poelmans, Dongmei Yu, S.-M. Shaheen, Tara Goodale, Vanessa M. Sinopoli, OCD Working Group of the Psychiatric Genomics Consortium, Noam Soreni, Gregory L. Hanna, Kate D. Fitzgerald, David Rosenberg, Gerald Nestadt, Andrew D. Paterson, Lisa J. Strug, Russell J. Schachar, Jennifer Crosbie & Paul D. Arnold. Translational Psychiatry


Genome-wide association study of pediatric obsessive-compulsive traits: shared genetic risk between traits and disorder

Using a novel trait-based measure, we examined genetic variants associated with obsessive-compulsive (OC) traits and tested whether OC traits and obsessive-compulsive disorder (OCD) shared genetic risk.

We conducted a genome-wide association analysis (GWAS) of OC traits using the Toronto Obsessive-Compulsive Scale (TOCS) in 5018 unrelated Caucasian children and adolescents from the community (Spit for Science sample).

We tested the hypothesis that genetic variants associated with OC traits from the community would be associated with clinical OCD using a meta-analysis of all currently available OCD cases.

Shared genetic risk was examined between OC traits and OCD in the respective samples using polygenic risk score and genetic correlation analyses. A locus tagged by rs7856850 in an intron of PTPRD (protein tyrosine phosphatase δ) was significantly associated with OC traits at the genome-wide significance level (p = 2.48 × 10−8). rs7856850 was also associated with OCD in a meta-analysis of OCD case/control genome-wide datasets (p = 0.0069).

The direction of effect was the same as in the community sample. Polygenic risk scores from OC traits were significantly associated with OCD in case/control datasets and vice versa (p’s < 0.01). OC traits were highly, but not significantly, genetically correlated with OCD (rg = 0.71, p = 0.062). We report the first validated genome-wide significant variant for OC traits in PTPRD, downstream of the most significant locus in a previous OCD GWAS. OC traits measured in the community sample shared genetic risk with OCD case/control status.

Our results demonstrate the feasibility and power of using trait-based approaches in community samples for genetic discovery.

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