Are you a control freak? 

Obsessive-compulsive disorder (OCD) is something else entirely. It is a condition marked by thoughts and images that chronically intrude in the mind and by engaging in repetitive behaviors aimed at reducing the associated anxiety. Some forms of the disorder can add an extra hour to the day's routine but some people are so disabled that they can't leave their homes.

Estimates say that OCD affects 1 percent of the U.S. population or more. Antidepressants known as SSRIs work for some, as does behavioral therapy.  Its causes and mechanisms are as much guessing as science. 

Like anything, it can be funny. Unless you have it. Link: The Resident Princess, who has OCD, so she can make those jokes.

A group of researchers say they have identified a genetic marker that may be associated with the development of obsessive-compulsive disorder.

"If this finding is confirmed, it could be useful," says study leader Gerald Nestadt, M.D., M.P.H., a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine. "We might ultimately be able to identify new drugs that could help people with this often disabling disorder, one for which current medications work only 60 to 70 percent of the time."

Nestadt and his team conducted a genome-wide association study, scanning the genomes of more than 1,400 people with OCD and more than 1,000 close relatives of people with the mental disorder. A significant association was identified in OCD patients near a gene called protein tyrosine phosphokinase (PTPRD). 

Nestadt says the genome-wide association study findings of a PTRPD-OCD link add to evidence that the genetic region they identified is important. The gene has already been shown in animals to be possibly involved in learning and memory, traits influenced by OCD in humans. Moreover, some cases of attention-deficit hyperactivity disorder (ADHD) have been associated with the gene, and OCD and ADHD have some symptoms in common. He says the gene also works with another gene family, SLITRK, which has also been associated with OCD in animals.

"OCD research has lagged behind other psychiatric disorders in terms of genetics," Nestadt says. "We hope this interesting finding brings us closer to making better sense of it — and helps us find ways to treat it."