Does our DNA make decisions for us?

In this week’s Proceedings from the National Academy of Science, Christina S. Barr and colleagues report that a mutation in the CRH gene is associated with increased stress-induced alcohol consumption in primates. What are the implications of this study and those like it? What does it mean if a DNA mutation can shape behaviors that affect our society?

First, let’s catch up on the basics. The CRH gene is the piece of DNA that encodes instructions to make corticotropin-releasing factor (CRF), a piece of cellular machinery required by our bodies for stress adaptation. Too much CRF activity can lead to increased anxiety or depression-like symptoms.

Barr’s research involves a mutation in a region of the DNA directly before the CRH gene, called the CRH promoter. In a sense, a gene’s promoter is like password protection for the gene. If the cell doesn’t use the proper combination of factors to satisfy the password, the instructions in the gene cannot be accessed. Other times, a faulty promoter will allow access to the gene too often. In the current study, the mutation in the promoter for CRH causes the cell to make too much CRF.

To determine if the CRH mutation affected stress-related behavior, Barr exposed young macaques to peer rearing (as opposed to mother rearing), an environment that is known to induce stress in these young animals. Next, Barr’s team measured the differences in alcohol consumption between normal macaques and those carrying the CRH mutation. After early stress exposure, the macaques with the CRH mutation consumed significantly more alcohol than the controls with a normal CRH gene.

Stop and think about this result for a moment. What does it mean if a gene mutation significantly affects a quantifiable behavior? To what extent does our genetic make-up contribute to the thousands of decisions every individual makes each day. The outcome of most decisions is benign; what one eats for breakfast or wears to work most likely won’t evoke a second thought. Other decisions, however, can have large impacts on society. The choice to consume excessive amounts of alcohol, engage in violent behavior, or disregard accepted social contracts can land a person in jail, if not worse.

Science progresses at an exponential pace. It is not unlikely that ten to twenty years from now, many more genes will be associated with specific behaviors. There will be a time when a jury will need to decide if a crime was committed with criminal intent or if the accused was at his DNA’s will. To properly handle these future scenarios, we as a society need to develop a basic understanding of cellular biology and learn how to assess the possible implications when something has gone amiss at the genetic level.

One hundred years ago, demons and devils were blamed for unacceptable behavior. One hundred years from now, who will be on trial: the perpetrator or his DNA? These are not questions for a science fiction novel or the next blockbuster film. These are relevant issues that warrant discussion based on educated reason.

Reference: Christina S. Barr et al. “Functional CRH variation increases stress-induced alcohol consumption in primates.” PNAS August 25, 2009. DOI: 10.1073/pnas.0902863106