A specific location on chromosome 17 may lead researchers to an understanding of abusive drug habits.
DNA samples from hundreds of families with at least two people addicted to opioids such as heroin, morphine or oxycontin point to a specific place on a chromosome that may contribute to addiction, according to a new study by Yale scientists.
This is the first study to search the entire genome looking for genes for drug abuse.
Dr. Joel Gelernter, a professor of psychiatry at Yale, has spent much of his career looking for such genes. It's a tough job, given that this behavior is probably a mix of many genes plus environmental influences, experts say. Pinpointing one or more genes that influence opioid dependence is challenging on many levels, including finding several generations of families willing to come forward and admit their abuse history.
Still, Gelernter and his colleagues identified 393 families with at least two people who abuse these types of drugs.
Scanning the entire genome, they found a location on chromosome 17 that showed activity among the DNA samples: This provides scientists with the neighborhood, then they need to find the right address.
Once they identify the actual gene or genes - the houses in the neighborhood - it will help scientists unravel the mysteries of what drives people to abuse these drugs.
"It's a useful step in tracking down unknown genes that have a role in opioid dependence and potentially other addictions," said Dr. David Goldman, chief of the laboratory of neurogenetics at the National Institute on Alcohol Abuse and Alcoholism. "The next step is to identify the gene itself."
The hope, of course, is to figure out the protein made by the gene and what it does. Then, scientists can try to develop drugs that block the negative effects of the gene.
It will also give them hints about what environmental factors create the risk.
"Once specific genes that increase or decrease risk are known," Gelernter said, "we will be in a better position to figure out exactly what the environmental factors might be."
The study appears next month in The American Journal of Human Genetics.
Some specific genes that are involved with alcohol abuse have been identified. There are two genes that protect against drinking abuse. One is acetaldehyde dehydrogenase-2: The less active form causes a buildup of the acetaldehyde and sets off a flushing reaction that is not comfortable for drinkers. The other gene is alcohol dehydrogenase, which makes acetaldehyde more rapidly. As a result, people drinking alcohol also experience a flushing reaction. But more active forms of these genes, which don't lead to flushing, may actually put people at risk for heavy drinking.
BY JAMIE TALAN, Newsday Staff Writer
