April 16, 2006
Genetic Variant Doubles Risk Of Obsessive Compulsive Disorder

A gene coding for a transporter for the neurotransmitter serotonin comes in a variation that greatly increases the risk of obsessive compulsive disorder.

Scientists at the National Institutes of Health’s (NIH) National Institute on Alcohol Abuse and Alcoholism (NIAAA) have identified a previously unknown gene variant that doubles an individual’s risk for obsessive-compulsive disorder (OCD). The new functional variant, or allele, is a component of the serotonin transporter gene (SERT), site of action for the selective serotonin reuptake inhibitors (SSRIs) that are today’s mainstay medications for OCD, other anxiety disorders, and depression.

“Improved knowledge of SERT‘s role in OCD raises the possibility of improved screening, treatment, and medications development for that disorder,” said Ting-Kai Li, M.D., Director, National Institute on Alcohol Abuse and Alcoholism. “It also provides an important clue to the neurobiologic basis of OCD and the compulsive behaviors often seen in other psychiatric diseases, including alcohol dependence.”

Approximately 2 percent of U.S. adults (3.3 million people) have OCD, the fourth most prevalent mental health disorder in the United States. Individuals with OCD have intrusive, disturbing thoughts or images (obsessions) and perform rituals (compulsions) to prevent or banish those thoughts. Many other individuals demonstrate obsessive-compulsive behaviors that do not meet OCD diagnostic criteria but alter the individuals’ lives.

Drs. David Goldman, Chief, and Xianzhang Hu, Research Scientist, in NIAAA’s Laboratory of Neurogenetics discovered the linkage aided by new functional analyses of the SERT genetic variant. The researchers first compared the genotypes of 169 OCD patients to those of 253 controls in a large U.S. patient population[i] and found that the OCD patients were twice as likely to have the variant. Then they studied transmission and non-transmission of the variant in a Canadian population[ii] of 175 OCD parent-child trios (two healthy parents and a child with OCD) and found that the risk variant was twice as likely to be transmitted from a parent to a child with OCD. Specifically, of 86 informative trios, 48 children carried the new risk variant and 26 did not.

Not surprisingly considering this result Stanford researchers found that a serotonin selective reuptake inhibitor, citalopram, provides some relief from OCD.

The pace of genetic studies like the one above happen at a rate mostly driven by the cost of DNA sequencing. When DNA sequencing costs fall orders of magnitude further then scientists will able able to perform massive comparisons of gene sequences between people with and without a large number of disorders and diseases. This will lead to the discovery of large numbers of other genetic variations that influence cognitive function and the risk of cognitive and other disorders.

People are going to become far more interested in the sequences of other people once we know how many different genetic variations influence behavior. Companies will want to hire managers with genetic profiles that mark them as bound to perform well. Ditto for engineers, sales reps, and other types of workers.

Also see my previous posts "Gene Mutations Cause Rare Form Of Obsessive Compulsive Disorder" and "Compulsive Hoarders Have Unique Brain Scan Patterns".

Share |      Randall Parker, 2006 April 16 06:28 PM  Brain Genetics

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