clipped from www.sciam.com

Smoking is the most potent known cause of lung cancer. The question is: Why do some longtime smokers come down with the deadly disease whereas others escape it? New research points to a genetic culprit that also was fingered as upping a person's likelihood of becoming hooked on cigarettes.

Two new studies link a variation in a gene residing on chromosome 15 (of a person's 23 pairs of chromosomes) to a heightened risk of developing lung cancer; a third study suggests that the same mutation  affects a person's tendency to become addicted to smokes and, by extension, develop the dreaded disease. Lung cancer is diagnosed in some 200,000 Americans and kills more than 150,000 each year.

The new research—published in both Nature and Nature Genetics—suggests that people with this genetic flaw have a 30 percent greater chance of developing the often-fatal illness. But the studies differ on the potential added risk of addiction.