[Genetic factors in obsessive-compulsive disorder: summary of genetic studies]

Obsessive-compulsive disorder (OCD) affects children and adults. As in most psychiatric disorders, genetic and environmental factors play an important role in the development of OCD. The symptom onset occurs at early age (before 18 years) in 80% of the cases; this early onset OCD has different clinical features compared to the adult form. Family studies suggest that childhood onset OCD is more heritable. In addition, there is male preponderance and a higher rate of comorbid tic and attention deficit hyperactivity disorder in the early onset OCD. These data imply that the early onset OCD might have different etiological background. In this review article we will shortly describe OCD symptoms, possible endophenotypes and neurobiological theories. After an overview of the applied genetic methods, we will summarize the genetic results of the OCD literature, especially candidate gene association studies. Finally, we will outline the possible future trends in psychiatric genetics.