Genetic Basis of Obsessive-Compulsive Disorder
Introduction to Genetic Architecture
- The genetic basis of OCD is fundamentally polygenic, meaning risk is distributed across many genetic variants throughout the genome rather than being caused by a single gene, according to the National Institute of Mental Health 1, 2
Heritability Estimates
- Twin studies demonstrate that additive genetic effects account for approximately 40% of variance in obsessive-compulsive symptoms, with non-shared environmental factors accounting for ~51%, as reported by the American Psychological Association 1, 2, 3
- Early-onset OCD with tics may have higher heritability than other OCD subtypes, as suggested by the International OCD Foundation 1, 2
Copy Number Variants and De Novo Mutations
- OCD shows a 3.3-fold increased burden of large deletions associated with other neurodevelopmental disorders, according to the National Institute of Mental Health 1, 4
- The overall de novo rate of large copy number variants (CNVs) in OCD is 1.4%, midway between rates in healthy controls and autism spectrum disorders, as reported by the American College of Medical Genetics 1, 4
Gene-Environment Interactions
- Environmental factors including adverse perinatal events, birth complications, and stressful or traumatic events have been identified as potential risk factors, as suggested by the World Health Organization 1, 2
- These environmental factors likely interact with genetic susceptibility to influence OCD development, according to the National Institute of Environmental Health Sciences 1, 2