New research from Wake Forest University School of Medicine suggests that some tobacco smokers with a genetic variation may be more susceptible to chronic obstructive pulmonary disease (COPD).

While harmless on its own, the genetic variant, in combination with smoking, may be a risk factor for COPD, researchers said.

The study—published online and scheduled to appear in a future print issue of the American Journal of Respiratory and Critical Care Medicine—involved over 1,000 men at least 40 years old who had smoked at least 1 pack a day for 20 or more years.