Abstract

Obsessive-compulsive disorders (OCD) are on the rise, and affected children, 1-2% of the general population, often are seriously impaired in their development. OCD is characterized by recurrent, intrusive and disturbing thoughts as well as by repetitive stereotypic behaviours. Depending on their age and developmental status, patients usually try unsuccessfully to suppress the obsessive thoughts and compulsive behaviours. The current state of genetic research on OCD and early-onset OCD is presented and discussed. OCD, especially early-onset OCD, has been shown to be familial. Convincing evidence indicates that both environmental and genetic factors substantially influence OCD. Various approaches, including linkage and association studies, yielded conflicting results as well as the notion that multiple genes of modest effect sizes, in interaction with environmental factors, cause vulnerability to the disorder. The phenotypic and genetic heterogeneity of OCD complicate the identification of specific genetic factors. Further studies have to be designed in consideration of subtypes, e.g. age at onset, symptom dimensions, or comorbid disorders.