Researchers at Washington University School of Medicine in St. Louis found that some adults who were sexually abused as children were protected from alcohol addiction due to a gene variant which offered them that protection against alcohol abuse.
According to the researchers, the finding could aid the development of therapies for alcohol dependence by offering suggestions for targeted treatments based on genetic traits and history of exposure to severe stressors.
Scientists estimate that about half the risk for alcoholism is encoded in a person's genes. The rest comes from environmental factors, such as age at first drink and exposure to extreme stress.
Other research has suggested that when the environmental risk factors occur during key periods of brain development, genes and environment working together can increase the likelihood an individual will become alcohol dependent.
Child sexual abuse is one of the environmental stressors that can interact with genes to significantly increase the risk for alcohol problems.
But a new study has shown that people with a particular pattern of genetic markers seem to be protected against alcohol problems, even if they were sexually abused as children.
Those who were protected carry a set of genetic variations that scientists call the H2 haplotype. Similar to a blood type, a haplotype is more than just a single genetic mutation.
It is a normally occurring pattern of gene variants that are statistically associated with one another so that when scientists find a few genetic markers, they can successfully predict what other genetic variations will occur within a particular region of DNA.
"We looked at how genes and environment interact. Our analysis included both sexual abuse and information about the DNA region that carries the H2 haplotype. People who carry that genetic pattern were protected against the risks for alcohol consumption and alcohol dependence typically associated with sexual abuse," said Elliot C. Nelson, lead author of the study.
Other sexual abuse victims in the study had the alternate genetic pattern known as the H1 haplotype. Those individuals had three times the risk of heavy drinking and alcohol dependence as those who had not been sexually abused.
"They drank much more alcohol and had a significantly greater risk for problems. But abuse victims with the H2 haplotype seemed to be completely protected against those risks," Nelson said.
The study has been published in the January issue of Addiction Biology.
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