Scientists studying the human genome have made a variety of amazing discoveries. Now, they say they've identified genetic factors that may be behind both obsessive-compulsive disorder and Tourette syndrome.

OCD is a common psychiatric disorder, affecting more than 2 million American adults. It's defined by the presence of obsessions and compulsions that can be a significant struggle. Tourette syndrome is a developmental disorder characterized by motor tics and at least one vocal tic. It usually appears in childhood and has genetic roots. Tourette syndrome affects one in every 100 people.

Two papers published in the journal of Molecular Psychiatry focused on the genetic level makeup of both of these conditions.

In the Tourette work, nearly 1,500 cases were studied. A signal within a specific gene was identified as the trouble spot. This gene encodes a program in the cerebellum, the region in the brain that covers motor control.

The in the OCD research, more than 1,400 cases were reviewed. At the genetic level, a strong signal was picked up near a gene that's highly expressed during childhood, when OCD is often diagnosed.

While neither study offers a reason why these conditions happen, understanding where they develop may help scientists move towards a better understanding of the genetic beginnings of both.