Strong Genetic Link for the Risk of Developing Alcohol Dependence

The nature versus nurture question is far from finally decided, but a recent study is helping us to better understand how nature may play a role in whether a person is vulnerable to forming a dependency on alcohol.

The U.S. Center for Disease Control and Prevention (CDC) reports that nearly 80,000 deaths in this country are connected to alcohol misuse, making it one of the top three causes of preventable deaths in the nation. Since alcoholism has such far-reaching public health impact, understanding what causes the disease is truly a national concern.

Other studies have looked into the heritability (nature) of alcoholism. In fact, research in 1999 claimed that the same genetic factors influence both nicotine and alcohol dependency. That study said that the shared genetic factors explained why alcoholics are so often also chain smokers. The researchers in this new study say that it is estimated that genetics are 50 percent responsible for influencing alcohol dependency in both men and women.

The most recent study initially involved over 3,800 adult subjects (1,761 men and 2,068 women) using the Semi-Structured Assessment for the Genetics of Alcoholism. This first wave of study was followed up by a genotype study of 2,600 Americans of non-Hispanic, European descent.

Researchers were particularly interested in genetic variations, referred to as common copy number variations or CNVs, which might be associated with alcohol dependency. The researchers found some of what they were looking for on chromosomes five and six. In these chromosomes, significant sections of the genome were not present and showed a modest link to vulnerability for alcohol dependency.

The team discovered CNVs on chromosome 5q13.2 and chromosome 6q14.1 which are in some way associated with risk for alcoholism. Chromosome five also factors in separate neurological diseases such as schizophrenia and autism and therefore invites further research. Chromosome 6 findings involved a region considered a gene desert so that further study, while warranted, will be more challenging.

The researchers emphasize the necessity of replicating these findings with other studies since the associations found thus far are considered modest. They also hasten to point out that the CNVs are not predictive of alcoholism. A person’s environment also plays a key role in their gene expression.

So far, researchers have only been able to identify a handful of influencing genes, but as tools for study become more precise more related genes may be found. Next-generation gene study and genotyping hold great promise. Even though there remains much to be learned, these preliminary findings do point to alcoholism as, at least in part, biomedical in nature. Further genome studies can be expected to improve our current understanding of how genetics impacts the disease.

This study is actually one part of a larger scope study entitled Study of Addiction: Genetics and Environment. The findings are scheduled for publication in September 2012 in Alcoholism: Clinical and Experimental Research.