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OCD, or obsessive-compulsive disorder, has been linked to a new genetic marker near the PTPRD gene. OCD is a behavioral disorder that is characterized by intrusive, anxiety-producing thoughts that result in repetitive and ritualistic behaviors, such as hand washing. People with OCD tend to repeat these behaviors, possibly for hours, just to try to get the unwanted thoughts to subside.
The study that reported the new genetic marker for OCD was published in the June volume of Molecular Psychiatry. Dr. Gerald Nestadt, who is a Professor of Psychiatry at Johns Hopkins University, led a team of scientists to search for a gene associated with OCD. They looked at the genomes (complete genetic material of an individual) of 1,406 people with OCD, 1,000 closely related family members of people with OCD and people without OCD or a relative that has OCD (control groups). The total number of genomes that were studied was 5,061.
The results of the study showed that OCD was associated near the protein tyrosine phosphokinase (PTPRD) gene on chromosome 9. In animal studies, the PTPRD gene has been associated with learning and memory. Speculation might suggest the PTPRD gene relation to OCD could be related to memory dysfunction. Could it be that people are possibly failing to remember correctly whether they washed their hands or not? If they are failing to remember they washed their hands, they might then become compulsive about washing their hands. Some people have OCD about whether they turned the stove off before they left the house. Their problem could be that they have a defective memory that they cannot rectify.
OCD is considered to be a disabling disorder and the report about a new genetic marker related to OCD is welcome news to many. Scientists, however, have been able to put together a story about OCD beyond the potential genetic basis. A study reported in Nature Reviews Neuroscience this month, reviewed the genetic and neurobiological bases for OCD as developed by scientists over the past few decades. In the review, they describe many genetic studies that have shown OCD to be familial and have hinted at genes or areas in DNA that are associated with OCD. This review states that it is clear that there are genetic factors that play a part in the manifestation of OCD.
This review article also describes the current view of the neurobiological basis for OCD. Based on a number of studies, the cortico-striato-thalamo-cortical (CSTC) model of OCD has been presented and has been the prevailing model of OCD. This neural system includes pathways from the frontal cortex to the more inner areas of the brain. Neurobiological studies of the brain have also included the new technology of optogenetics in which light is used to stimulate certain areas of a brain. Use of optogenetics in mice caused them to exhibit excessive grooming behavior, which is similar to OCD behavior in humans.
The newly reported genetic marker for OCD is another step in the journey towards understanding the biological basis for OCD. Every step that moves the research ahead aids in the understanding of how to help those with OCD so that they can be free of the tiresome burden of repetitive behaviors.
By Margaret Lutze