Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mutant gene linked to obsessive compulsive disorder

24.10.2003


Analysis of DNA samples from patients with obsessive compulsive disorder (OCD) and related illnesses suggests that these neuropsychiatric disorders affecting mood and behavior are associated with an uncommon mutant, malfunctioning gene that leads to faulty transporter function and regulation. Norio Ozaki, M.D., Ph.D., and colleagues in the collaborative study explain their findings in the October 23 Molecular Psychiatry.

Researchers funded by the National Institutes of Health have found a mutation in the human serotonin transporter gene, hSERT, in unrelated families with OCD. A second variant in the same gene of some patients with this mutation suggests a genetic "double hit," resulting in greater biochemical effects and more severe symptoms. Among the 10 leading causes of disability worldwide, OCD is a mental illness characterized by repetitive unwanted thoughts and behaviors that impair daily life.

"In all of molecular medicine, there are few known instances where two variants within one gene have been found to alter the expression and regulation of the gene in a way that appears associated with symptoms of a disorder," said co-author Dennis Murphy, M.D., National Institute of Mental Health (NIMH) Laboratory of Clinical Science. "This step forward gives us a glimpse of the complications ahead in studying the genetic complexity of neuropsychiatric disorders."



Psychiatric interviews of the patients’ families revealed that 6 of the 7 individuals with the mutation had OCD or OC personality disorder and some also had anorexia nervosa (AN), Asperger’s syndrome (AS), social phobia, tic disorder, and alcohol or other substance abuse/dependence. Researchers found an unusual cluster of OCD, AN, and AS/autism, disorders together with the mutation in approximately one percent of individuals with OCD.

The scientists analyzed DNA from 170 unrelated individuals, including 30 patients each with OCD, eating disorders, and seasonal affective disorder, plus 80 healthy control subjects. They detected gene variants by scanning the hSERT gene’s coding sequence. A substitution of Val425 for Ile425 in the sequence occurred in two patients with OCD and their families, but not in additional patients or controls. Although rare, with the I425V mutation found in two unrelated families, the researchers propose it is likely to exist in other families with OCD and related disorders.

In addition to the I425V mutation, the two original subjects and their two siblings had a particular form of another hSERT variant, two long alleles of the 5-HTTLPR polymorphism. This variant, associated with increased expression and function of the serotonin transporter, suggests a "double hit," or two changes within the same gene. The combination of these changes, both of which increase serotonin transport by themselves, may explain the unusual severity and treatment resistence of the illnesses in the subjects and their siblings.

"This is a new model for neuropsychiatric genetics, the concept of two or maybe more within-gene modifications being important in each affected individual. This is also probably the first report of a modification in a transporter gene resulting in a gain rather than a decrease in function," said NIMH Director Thomas Insel, M.D.

SERT allows neurons, platelets, and other cells to accumulate the chemical neurotransmitter serotonin, which affects emotions and drives. Neurons communicate by using chemical messages like serotonin between cells. The transporter protein, by recycling serotonin, regulates its concentration in a gap, or synapse, and thus its effects on a receiving neuron’s receptor.

Transporters are important sites for agents that treat psychiatric disorders. Drugs that reduce the binding of serotonin to transporters (selective serotonin reuptake inhibitors, or SSRIs) treat mental disorders effectively. About half of patients with OCD are treated with SSRIs, but those with the hSERT gene defect do not seem to respond to them, according to the study.

Any vulnerability to OCD from gene effects most likely interacts with events in the environment like stresses, other factors like gender, and treatments, Murphy said. By examining the serotonin transporter gene’s mutation and flawed regulation in individuals with OCD, the new research provides insights on transporter function and on the consequences of the variant, which may lead to tests to identify and treat mental illness.

A related study in the August 2003 Molecular Pharmacology tested consequences of the hSERT variant. The report is considered the first to identify a coding mutation in a transporter linked to a psychiatric condition. Researchers found that the I425V mutation of hSERT increased the transport activity of this protein, capturing more serotonin and most likely reducing effects at the receiving neuron’s receptors, outperforming the common transporter. The mutant molecule was not regulated normally and did not respond to cell signals that activate the common form of the transporter. Gary Rudnick and Fusun Kilic, Yale University School of Medicine, with Murphy at NIMH, conducted this research, which was funded by the Rockefeller Brothers Fund, the National Alliance for Research on Schizophrenia and Depression, and the National Institute on Drug Abuse (NIDA).

Participants in the study published in Molecular Psychiatry were: Norio Ozaki, Fujita Health University School of Medicine, Toyoake, Aichi, Japan, whose early work on the project was supported by awards from the NIMH Intramural Programs of the National Institute of Alcohol Abuse and Alcoholism (NIAAA) and the NIMH; David Goldman, NIAAA; Walter Kaye and Katherine Plotnicov, University of Pittsburgh Medical Center and Western Psychiatric Institute and Clinic; Benjamin Greenberg, Butler Hospital and Brown University School of Medicine; Jaakko Lappalainen, Yale University School of Medicine; and Gary Rudnick, Department of Pharmacology, Yale University School of Medicine; Dennis Murphy, NIMH Laboratory of Clinical Science.

Constance Burr | EurekAlert!
Further information:
http://www.nimh.nih.gov

More articles from Studies and Analyses:

nachricht Physics of bubbles could explain language patterns
25.07.2017 | University of Portsmouth

nachricht Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>