KNOWLEDGE YOU CAN USE

KNOWLEDGE YOU CAN USE
Can a Gene Nudge Us toward Novelty-Seeking (and Spicy Foods)?

On human chromosome 11 there is a gene called DRD4. This gene carries the instructions for building a receptor for the brain chemical dopamine within the membranes of many of your brain cells. All humans have the dopamine receptor gene DRD4 which helps control dopamine, a chemical messenger that alters the activity of the brain’s pleasure centers and influences initiative and motivation. A short sequence near the beginning of the DRD4 gene, called “promoter polymorphism–521C/T,” has two different variants, alleles C and T. Dopamine activity is increased in individuals with one or two copies of the T allele, and decreased in individuals with the CC genotype.

Question 7.11

Q: Can a single gene influence your personality? In 2000, researchers reported that individuals carrying two copies of the C allele for the DRD4 gene, as opposed to zero or one copy of the C allele, were more likely to exhibit certain personality traits, particularly novelty-seeking. The subjects in the study responded to a commonly used questionnaire, called the temperament and character inventory. They ranked how well certain statements described them, such as “I have sometimes done things just for kicks or thrills” or “I think things through before coming to a decision.” The subjects were then evaluated for seven dimensions of personality traits. When it came to their score for “novelty-seeking,” there was a small but statistically significant difference in how the subjects scored, depending on their genotype for this DRD4 gene.

By 2008, 11 studies had been published on the relationship between the CC genotype and novelty-seeking. In a “meta-study” that evaluated all the published findings together, researchers concluded that these studies demonstrated a significant association between novelty-seeking and the –521C/T genotype. They summarized the results graphically.

Researchers have subsequently reported a variety of behavioral differences among people with higher novelty-seeking scores, including increased propensities for engaging in high-risk sports, alcohol and drug consumption, and attraction to high-risk vocations. These people have even been reported to show a preference for spicy foods!

Question 7.12

Q: Do you want your employers or insurance companies to know which alleles you carry for the DRD4 gene? Information about your genetic predisposition for diseases such as breast cancer or colon cancer can put you at risk for discrimination. Might a person be at risk for discrimination based on his or her genotype for the DRD4 gene? Should it be taken into account that the personality differences influenced by DRD4 are small, that they are affected by other genes, and that there is tremendous variation in personality traits that is unrelated to the DRD4 gene? Would you want to know what your genotype is? Why?

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