SNPs on Chromosome 15 Associated with Smoking and Lung Cancer

by Dr. Hsien-Hsien Lei
Posted April 3, 2008 in DNA and Disease

Despite recent downsizing, deCODE Genetics has published a new study in Nature on the genetics of smoking and lung cancer. Two other studies with the same focus were also published in Nature and Nature Genetics.

All three studies identified regions on chromosome 15 that are associated with nicotine dependence, lung cancer, and peripheral artery disease. The deCODE study focused on SNP rs1051730 located on chromosome 15q24 in the CHRNA3 nicotine acetylcholine receptor. People with one copy of the “T” version of this SNP had:

• 30% increase in risk of lung cancer
• 20% increase in risk of peripheral artery disease

Half of people of European descent have at least one copy of the higher risk SNP and 10% may have two copies which increases their cancer risk by 80%.

• A smoker has a 15% risk of lung cancer over his/her lifetime
• Smokers with two copies of the T SNP variant has a 23% risk of lung cancer.
• People who’ve smoked less than 100 cigarettes in their lifetime have a <1% risk of lung cancer.

Researchers also hypothesized that the higher risk T SNP variant may influence a person to smoke more cigarettes and become more easily dependent on nicotine. The deCODE study found that those with one copy of the T SNP variant smoked an additional cigarette per day than those without the variant. Two copies of the T SNP variant was associated an two more cigarettes per day.

Last month for No Smoking Day in the UK, Alicia Sparks at Mental Health Notes gave five reasons why smoking is dangerous to her mental health. Aside from the obvious negative health effects, she says smoking does not make her happy, makes her worry, gives her too much to deal with, stresses her out, and makes her feel guilty. What do you think about smoking?

NB: Bioethicist Arthur Caplan discussed the possibility of lung cancer genetic testing in the New York Times.

Such testing could carry risks all its own, bioethicist Arthur Caplan of the University of Pennsylvania warned. People who have been found to have a genetic predisposition to addiction and lung cancer could find it harder to get health or life insurance, or their employer might drop their coverage, he said.

”The good news is that getting these risk estimates will help focus anti-smoking campaigns, and some people will want to voluntarily get into anti-addiction programs early, where they will probably work better,” Caplan said in an e-mail. But if such testing is done, it should be voluntary, and the results should be kept private, he said.

Update: Dr. Ann Turner comments on these findings at GENEALOGY-DNA.

The SNP, rs1051730, has already been incorporated into reports for deCODEme customers (literally within a few minutes of the press release). It is also tested by 23andMe, but it is not on the Affymetrix 6.0 chip used by SeqWright and a new company http://geneessence.com. However, the Affy chip could have a near-by SNP that would be in linkage disequilibrium with rs1051730.

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4 Comments »

Comment by Alicia Sparks, NAMI Affiliation Leader

2008-04-03 18:14:12

This is scary stuff.

The fact that I understand next-to-nothing about DNA aside, this post actually makes a lot of sense to me. I know people who smoked for several years, and had no problem quitting cold-turkey, just on a whim one day. Then, I know people who smoke who would never be able to do that. I also know people who’ve smoked nearly all their lives and have no smoking-related health problems (such as lung cancer), and I know folks who developed lung cancer very early on (both smokers and nonsmokers). The information here kind of helps me make sense of all that.

For myself, I would be very interested in lung cancer genetic testing. Of course, like Caplan suggested, I’d like it to be kept private.

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Pingback by Personalized Genetics: It’s getting interesting « ScienceRoll

2008-04-03 23:26:17

[...] reported their scientists identified a genetic variant that confers nicotine dependence. Later, Hsien-Hsien Lei said some words about it. And of course, Steve Murphy expressed his opinion as well: Bottom Line, if [...]

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Comment by jhay

2008-04-04 04:47:38

What about the risk percentages for non-smokers but victims of second-hand smoke?

They too carry the same genes don’t they?

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Pingback by Strat-Cons Blog » Blog Archive » Tabaquismo a ultranza: ¿Ampararse por genética?

2008-04-15 04:09:47

[...] El pasado 3 de abril, la Dra. Hsien-Hsien Lei, publicó en Eye in DNA un análisis de donde podemos [...]

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