About Cloninger's Personality Dimensions

   The Gene and Personality

   Dean Hamer, Ph. D., is Chief of Gene Structure and Regulation at the National Cancer Institute's Laboratory of Biochemistry.  Coauthor Peter Copeland is an award winning journalist.
   According to the authors, certain genes affect dopamine or serotonin to make difference of personality traits.  Some researchers say that certain HLA types might affect neuronal post-synaptic membrane sensitivity to central neurotransmitters -- such as dopamine -- because both chemical structure is much the same.  So, ABO blood type might affect dopamine and/or serotonin to make difference of personality traits if structure is much the same ...

   Living with Our Genes -- Why They Matter More Than You Think --(1998) by Dean Hamer, et. al. (from pp. 76-80)

     Murphy and Lesch's persistence had paid off. They'd found an inherited variation in DNA that clearly affected serotonin transport. Here was a little button effectively controlling levels of serotonin in the brain. Now the key question was, What did this "genetic Prozac" do in human beings? What effect did it have on temperament?

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   The final analysis was to look at Cloninger's predictions. He had theorized that serotonin would be involved in harm avoidance, and now we had a chance to test the theory. He was right. We found a significant correlation between this DNA region and the trait he called harm avoidance, which we could estimate by mathematically rearranging the questions from the five-factor test. There was no correlation for any of the other traits he identified. This was the second confirmation of Cloninger's theory. He also had guessed right that dopamine was linked to novelty seeking, and now he was proved right that serotonin was linked to harm avoidance. His model of personality was starting to look pretty good indeed.
   There was one intriguing twist to the story. The people with the highest level of anxiety-related traits had the short version of the gene promoter. This meant that where the serotonin transporter was least efficient, people had the most anxiety. This was the opposite of the Eli Lilly explanation for how serotonin works; it should have been the lowered serotonin transporter levels that were associated with decreased harm avoidance. Our results were more consistent with the "classical" model that serotonin causes rather than alleviates anxiety, depression, and other elements of harm avoidance.
   It's difficult to draw any firm conclusion yet about the direction of serotonin action, however, because it's possible that a lifelong decrease in serotonin transporter gene expression actually decreases serotonin signaling through a feed back or compensatory mechanism. What's really needed is a direct way to measure serotonin signaling in the living brain -- but that's not available yet.
   Our study not only confirmed the connection between the serotonin transporter and harm avoidance, but it also provided the first conclusive evidence that the multiple facets harm avoidance are connected at the level of the genes. That's because the differences in the DNA correlated equally well with several different aspects of harm avoidance: anxiety, depression, hostility, pessimism, and fatigability. Thus the results were a satisfying confirmation of the claim that a single set of genes -- in this case just one gene -- can influence distinct traits that are obvious in real people.

REFERENCE:
Lesch, Klaus-Peter, Dietmar Bengel, Armin Heils, Sue Z. Sabol, Bejamin D. Greenberg, Susanne Petri, Jonathan Benjamin, Clemens R. Muller, Dean H. Hamer, and Dennis L. Murphy. "Association of Anxiety Related Traits with a Polymorphism in the Serotonin Transporter Gene Regulatory Region Science 274,1527-31 1996.

REFERENCE:
Lesch, Klaus-Peter, Dietmar Bengel, Armin Heils, Sue Z. Sabol, Bejamin D. Greenberg, Susanne Petri, Jonathan Benjamin, Clemens R. Muller, Dean H. Hamer, and Dennis L. Murphy. "Association of Anxiety Related Traits with a Polymorphism in the Serotonin Transporter Gene Regulatory Region Science 274,1527-31 1996.

   Underlined sentences are authors' conclusions.  After all, dopamin is connected to novelty-seeking and seretonin connected to harm avoidance. Might Type B affect dopamine and Type A affect seretonin?   That can explain the difference of personality by blood type ...