The more we delve into our DNA, the more we find
that we are predisposed to some disease, condition, or behavior. The latter
predisposition is the most difficult one to get to terms with as it can suggest
an excuse or lack of responsibility for that behavior.
So what about habit forming behaviors such as
smoking? Well, a predisposition to smoking does seem to lurk along those
twisted strands of amino acids. Verde et
al took 206 Spaniards and unraveled their DNA. 126 of these were regular
smokers in the age range 20 to 84. Half were women. Nearly half of the smokers
were diagnosed with lung cancer, so they certainly shouldn’t have been smoking.
The 80 controls were people who had never smoked, ever.
After sifting through lots of candidate sections of DNA,
the common thread appeared as the gene that is responsible for the metabolism
of nicotine through the production of the enzyme nicotine C-oxidase. A
deficiency of that enzyme correlated with the smoking behavior.
Interestingly, the variations around the genes
affecting the brain that interact with nicotine, serotonin, opioids or
cannabinoids are not correlated with smoking status. It is just our difficulty
in metabolizing it that makes us open the pack.
Maybe cursing the polymorphism of our CYP2A6 phenotype might help salve our
conscience short term when we yield to temptation, but it will weaken rather than
strengthen our resolve.
