Dimensional phenotypes and molecular genetic studies of obsessions, compulsions and tics

Obsessive-Compulsive Disorder (OCD) is characterized by recurrent repetitive thoughts/images (obsessions) that cause fear and/or create tension and lead to repetitive behavior to reduce this anxiety or tension (compulsions). Gilles de la Tourette syndrome (GTS) is characterized by repetitive unwanted muscle movements (tics) and sounds or words. Some forms of OCD and GTS may be genetically related. The search for genes for OCD and GTS is complicated by the variety of symptoms. One of the aims of this thesis was to distinguish homogeneous symptom dimensions.