BUDAPEST, HUNGARY, March 9 – Ever wonder why some women seem to be more ill-tempered than others? University of Pittsburgh researchers have found that behaviors such as anger, hostility and aggression may be genetic, rooted in variations in a serotonin receptor gene. Indrani Halder, Ph.D., of the Cardiovascular Behavioral Medicine Program at the University of Pittsburgh, will present the findings today at the American Psychosomatic Society's Annual Meeting, held in Budapest, Hungary.
Previous studies have associated the hormone serotonin with anger and aggression in both humans and animals and have shown that increased serotonin activity is related to a decrease in angry and aggressive behaviors. In the study being presented today, researchers sought to determine if this relationship was genetically determined. The study is the first to look at the relationship between variations in the serotonin receptor 2C gene and anger and hostility.
Completed at the University of Pittsburgh's Behavioral Physiology Laboratory, the study looked at 550 unrelated women of European descent. In order to find normal variations in genes and behavior, the women were not prescreened for behavioral type. Researchers found that those who had one or both of two alterations in the promoter region of the serotonin receptor 2C gene were more likely to score lower on two common tests for anger, hostility and aggression.
But not so fast. Robert Plomin, who has spent years trying to find gene alleles that produce differences in intelligence, thinks the search for genes that influence cognitive qualities is so hard that these latest results are unlikely to be correct.
"Individual differences in aggression and anger are influenced by genes -- as are all personality traits -- but progress in identifying the genes has been slower than researchers expected," added Prof Robert Plomin, deputy director of the Social, Genetic and Development Psychiatry Centre, London. "Thousands of reports of this gene or that gene being related to complex traits or common disorders in the end fail to replicate, not just for behaviour but also for medical problems such as dementia and heart disease."
I am very keen to find out which genetic variations create differences in personality, intelligence, and other aspects of cognitive function. But since Plomin and other scientists think each mental trait is controlled by many gene alleles and each variation contributes only a small amount to the total result. So identifying a genetic influence above the background noise of other genetic variations and environmental influences is very difficult.
The solution to this problem? Huge decreases in the cost of DNA testing. Gene chips that test hundreds of thousands of single letter DNA differences at once have already hit the market quite recently. We need gene testing cheap enough that thousands or tens of thousands of genetic variations can be checked in each person in a study. We also need costs so low that thousands or even tens of thousands of people can get checked at once. Then scientists will be able to control for enough genetic variations at once to identify those that are really influencing cognitive function.
We are waiting for advances in gene chip and microfluidics biotechnology so that scientific questions about human genomes become easy to answer. Most of what we are going to learn about human genetic differences is going to be figured out in a short period of time after decades of attempts to answer those questions. The instrumentation advances are more important than any one or ten of the scientific discoveries that will come from them.
|Share |||Randall Parker, 2007 March 13 12:17 AM Brain Genetics|