- New York Times 07/30/02; Eric Nagourney

The Gene

The gene publicized as the "anxiety gene" is the human serotonin transporter gene (SLC6A4) located on the 17th chromosome. There are two common allele variants exist in the variable repeat sequences of the promoter region of the SLC6A4 gene that are called short (s ; recessive) and long (l ; dominant). The homozygous (l) has been shown to phenotypically create more Serotonin hydroytrptamine transporter (5-HTT) than the heterozygous or homozygous (s) genotype.

Press Releases

The Philadelphia Inquirer "Researchers Link Anxiety to Genetics" By Faye Flam, 19 July 2002

The Philadelphia Inquirer portrays an accurate and relatively thorough story on the article that was published in Science magazine’s July edition concerning the SLC6A4 gene. The news article starts by saying that the gene the researchers identified may play a role in the human emotion of anxiety, and that the gene is one of many factors that contribute to anxiety. The Inquirer makes it clear throughout the article that SLC6A4 is a behavior related gene and not the singular reason for anxiety. Likewise, the quotes used in the news article from the researchers that conducted the study on SLC6A4 gave an accurate depiction of the reality of their findings. One such quote states, “ any one gene alone cannot control a person’s temperament ”. To further clarify that their study does not offer a simple wonder cure for anxiety; the paper gives an analogy which the general public can easily grasp. The Inquirer makes a comparison between SLC6A4 and anxiety to fair skin and skin cancer, explaining that having fair skin only makes a person more susceptible to skin cancer. This paper did a good job of sticking to the facts and not over hyping the the findings in the study just to sell their publication at the news stands.

BBC News "Genetic Link to Anxiety" Posted : 19 July 2002

The BBC News coverage uses the Internet as a medium for their coverage of the study published in Science magazine’s July edition. The use of the Internet by the BBC News results in a more truncated article that does not allow for an extremely in depth and explanatory article. Whether by design or not, at first glance the very compressed article could give the impression that the study has concluded the reason for anxious behavior. However, the article does make some distinctions in their coverage by stating that the SLC6A4 gene is one factor among many others that cause anxiety. However, the BBC News does not offset their statements to emphasize that the SLC6A4 gene isnt’t the sole reason for anxious behavior. Only after scrolling down to the very last page of the article there are short two paragraphs that attempt to make it clear that the SLC6A4 gene is at best only one contributor to a person’s predisposition for anxious behavior. Once again whether it was the BBC’s design or not, a person could get the wrong impression by reading the first part of the story on the front page, and not bother to scroll to the end of the article to get the full story.

The New York Times " Fearing More Than Fear Itself " By Eric Nagourney, 30 July 2002

This article exemplifies the stereotype of the media sensationalizing a story in order to attract readers. The title of the news article itself is a sensationalized gimmick geared toward sucking in readers. In fact the title doesn't’t really represent anything about the study of the SLC6A4 gene. Throughout the article there is a medley of literary gimmicks that give the reader the impression that the cure to anxiety has been discovered in a single gene. One gimmick that the article uses to give the appearance of credibility is to use full scientific terms such as “magnetic resonance imaging” instead of the commonly used “MRI” which the public is familiar with. The article only briefly says once in the middle of a paragraph “the gene SLC6A4 plays a role in anxiety disorders”. The article goes on to talk about the amygdala, the part of the brain responsible for feelings of anxiety, which is a part of the brain that the study focused on though the news article doesn’t make a reference to the study when discussing the amygdala. Once again, the writer using words like “amygdala” to make the article seem more credible. Overall, this article did not do the science behind it any justice. Rather this article uses science to sell its paper, nothing more.

Article in Science,19 July 2002

All three of the articles in the popular media were directly referencing the same study that came out in Science magazine in July 2002. The study’s purpose was to attempt to link the promoter region of the serotonin transporter gene (5-HTT), SLC6A4, to the human emotion of anxiety induced by external environmental factors. The SLC6A4 promoter region is polymorphic that has two different alleles, a long (l) allele, which is dominant, and the recessive short (s) allele. The short allele is associated with reduced expression and function of 5-HTT. The greatest expression of 5-HTT occurs in the dominant homozygote (l) whereas the heterozygote expresses less 5-HTT, and recessive (s) homozygote genotype expresses the least 5-HTT. Thus those who have less of the serotonin transporter will consequently have less serotonin uptake, which will result in heightened levels of anxiety. The area of the brain where serotonin uptake is localized is in the amygdala. When the amygdala is most excited when a person is in a stressful situation. The study examines the amygdala with functional magnetic resonance imaging (MRI) while simultaneously exposing the subject to stressful stimuli. The MRI picks up increases in blood oxygen level dependences, which are caused by stress, and the serotonin reuptake in the brain. A greater blood oxygen level dependence observed with the MRI indicates a low level of serotonin reuptake and high level of stress.

Left figure is the picture of the functional MRI picking up activity in the amygdala. Right figure showing examples of the woman showing "emotional" facial expressions. * permission pending from http://www.heise.de/tp/deutsch/inhalt/lis/12945/1.html *

The hypothesis of the group conducting the study was that the individuals that have either one or two copies of the short allele will have low levels of serotonin reuptake, and therefore will be predisposed to a more anxious response when put under stress. Conversely, those individuals who have the homozygous dominant (l) genotype will have higher levels of serotonin reuptake and therefore are not as likely to show signs of anxiety when put under stress.
The study sample is twenty-two individuals that are put into two groups of eleven. The two groups are named group “l” that all have the homozygous (l) genotype, and group “s” which is a combination of the heterozygous genotype and the homozygous (s) genotype. Each individual is shown pictures of a woman’s face that express different “facial” emotions. While the test subject is observing the pictures the subject is being monitored by the functional MRI. The tests subjects are also given “memory tasks” and “emotional tasks” before being monitored by the MRI to ensure that the entire sample group is in the same state of mind.
As predicted by the group conducting the experiment the “s” sample group has a 2.5% higher mean change in their blood oxygen level dependence than the “l” sample group after being shown the stimulus pictures. Thus the group conducting the study concluded that the polymorphism in the promoter region of the SLC6A4 gene must play some role in the emotional response to stress.
The conclusions made at the end of the article were backed up by the data that was presented in the article. However, there were a few points concerning the data that need to be scrutinized more carefully. The fact that the “s” group was a mixture of the heterozygous and homozygous recessive genotype causes confusion. In a graph presented in the article each individual was plotted vertically on the x-axis according to which group they were in, where the y-axis was the % change in blood oxygen level dependence. Since each individual was clumped vertically into an “s” group or “l” group on the graph it is impossible to distinguish between the heterozygotes and the recessive homozygotes. There are many points of overlap between the “s” group and the “l” group on the graph. It is entirely possible that the homozygous dominant genotype had a greater overall change in the blood oxygen level dependence than the homozygous recessive genotype according to the graph. The article states that there was an overall 2.5% higher change in the blood oxygen level dependence of group “s” than in group “l”. The question becomes; is 2.5% a significant change? The article says that it isn’t a significant change, however this insignificance in percent blood oxygen level dependence is due to a small sample size. Who is to say that a larger sample size will change anything? Once more point that needs to be examined in this article are the “emotional tasks” and the “memory tasks” that are given to the test group. The purpose of these tasks were to make sure that the test group was in the same state of mind, so that outside factors such as personal crisis, would not skew the results. Unfortunately, these “tasks” are never explained or supported anywhere in the article. How are we to know that the pictures of the woman and not a personal crisis determined the test subjects’ blood oxygen level dependence?

Comparison Between Popular Press and Science Article

The purpose of this web page is to show how discoveries in genetics can be sensationalized to the public through the popular media. Though sometimes even the publications of works within the scientific community can be misleading. Two out of the three popular media sources, The Philadelphia Inquirer and BBC News, were surprisingly quite accurate in the reality of the study done on the SLC6A4 gene. However, The New York Times was absolutely guilty of over hyping and sensationalizing the study that was discussed. The study that was basis for the article "Fearing More Than Fear Itself" barely even makes a reference to the article and came off to the reader as if the journalist himself was and expert on serotonin transporter promoter regions. By the same token the article in Science "Serotonin transporter genetic variation and the response of the human amygdala" that was published in Science magazine had some discrepancies in itself that weakens the conclusions that the study makes. As a result the popular media is adverting to the public something that is not yet entirely accepted in the scientific community.

References

1. Egan, M. F.; Hariri, A. R.; et al. Serotonin Transporter Genetic Variation and Response of the Human Amygdala. Science. Vol. 297. No. 5580: 400 - 403.

2. Flam, Faye. " Researchers Link Anxiety to Genetics ". The Philadelphia Inquirer. 19/07/2002

3. Nagourney, Eric. " Fearing More Than Fear Itself ". The New York Times. 30 July 2002

4. Anonymous. " Genetic Link to Anxiety ". BBC News. 19/07/2002 <http://news.bbc.co.uk/1/hi/health/2135704.stm>

 

Links

Nucleotide sequence

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=nucleotide&list_uids=10803048&dopt=GenBank

GeneCard for SLC6A4

http://bioinformatics.btk.utu.fi/genecards/cgi-bin/carddisp?SLC6A4

BBC News Atricle

http://news.bbc.co.uk/1/hi/health/2135704.stm

 

patoran@davidson.edu