US researchers said Tuesday they have discovered a gene variation that has the potential to protect against alcoholism, and which could lead to a preventative treatment.
The gene variant known as CYP2EI is linked to people's response to alcohol, and for 10 to 20 percent of people who have it, just a few glasses leads them to feeling more drunk than the rest of the population, said University of North Carolina researchers at the Chapel Hill School of Medicine.
Earlier studies have shown that people with strong reactions to alcohol are "less likely to become alcoholics later in life, but the genetic basis of this finding was not clear," researchers said in the study published online Tuesday in the journal Alcoholism: Clinical and Experimental Research (ACER).
To distinguish the genetic characteristics of alcoholism, lead study author Kirk Wilhelmsen and his team gathered hundreds of pairs of college-age siblings with at least one parent who was an alcoholic.
The study participants were given an alcohol/soda cocktail equivalent to about three drinks and were questioned on how they felt out of the options: I feel drunk, I don't feel drunk; I feel sleepy, I don't feel sleepy.
Researchers used "genetic analyses called linkage and association to hone in on the gene region that appeared to influence how the students perceived alcohol," said the study.
This CYP2EI gene -- located in the brain, not the liver -- has long been known to hold an enzyme for metabolizing alcohol, and generates molecules known as free radicals.
"It turns out that a specific version... of CYP2E1 makes people more sensitive to alcohol, and we are now exploring whether it is because it generates more of these free radicals," said Wilhelmsen.
"This finding is interesting because it hints at a totally new mechanism of how we perceive alcohol when we drink," he added, noting that the conventional idea for "getting drunk" holds that alcohol affects how neurotransmitters -- the molecules communicating between brain neurons -- work.
Drugs that can be created to induce the CYP2E1 gene could eventually make people more sensitive to alcohol or help sober them up if they have had to much, Wilhelmsen said.
"Alcoholism is a very complex disease, and there are lots of complicated reasons why people drink. This may be just one of the reasons," he added.