Researchers have been unable to confirm a widely publicized study linking a gene to a predisposition to alcoholism.
The finding does not necessarily challenge the idea that genetic predisposition is a significant risk factor for alcoholism. But the researchers said it suggests that more work will be needed to identify any gene or genes that may be at fault.
In April, researchers reported that defects in a gene involved in the transmission of messages between brain cells strongly predisposed people to become alcoholics.
But in a study being published today in the Journal of the American Medical Association, a group of federal investigators report that they could not find such an association with the gene.
Dr. David Goldman, the principal investigator and chief of the section on genetic studies at the National Institute of Alcohol Abuse and Alcoholism, and his colleagues said they looked for the gene in 10 alcoholics, 127 people who were not alcoholics, and two large families that had alcoholic members.
But one of the scientists who made the original observation, Dr. Kenneth Blum of the University of Texas Health Sciences Center in San Antonio, said the discrepancy might be tied to differences in the people studied.
Blum and his fellow researcher, Dr. Ernest P. Noble of the University of California in Los Angeles, studied people who were such intransigent alcoholics that they actually died of the disease.
Goldman studied a group that included less severe alcoholics.
"They are such different populations that you can't compare the studies," Blum said.
Goldman agreed that he studied less severely affected alcoholics.
"There could be a subgroup of alcoholics who still have that marker," he said.
The study by Blum and Noble was published in the April 18 issue of the Journal. It gained vast attention. The investigators examined the brains of 35 people who died of alcoholism and compared them with the brains of 35 people who were not alcoholics. They found that the alcoholics had a variant of a gene that could determine the way the brain responds to things such as pleasure-seeking behavior.
The gene was a blueprint for a dopamine receptor, a protein that protrudes from brain cells and latches onto dopamine, a chemical that transmits nerve impulses. Researchers had previously gleaned hints that dopamine plays a role in behavior like alcoholism.