WEDNESDAY, March 11 (HealthDay News) -- Genes may be the reason why one-quarter of smokers develop chronic obstructive pulmonary disease (COPD), while the rest aren't afflicted with the serious breathing problem, U.S. researchers conclude.

They studied a gene called ADAM33 in 880 long-term heavy smokers with and without COPD. Previous research has linked ADAM33, which is located on chromosome 20, with asthma.

The researchers from the Wake Forest University School of Medicine and Saint Louis University identified five single nucleotide polymorphisms (SNPs) -- human DNA sequence variations -- in ADAM33 that were more common in smokers with COPD than in those without the disease.

There was a particularly strong link between an SNP called S1 and lung abnormalities.

"Functional studies will be needed to evaluate the biologic significance of these polymorphisms in the pathogenesis of COPD," wrote the authors of the study, which was published in the journal Respiratory Research.

COPD, which includes chronic bronchitis and emphysema, causes a progressive decline in lung function. Almost 90 percent of COPD cases are caused by long-term cigarette smoking, but only 25 percent of long-term smokers develop COPD.

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• COPD (Chronic Obstructive Pulmonary Disease)
• Genes and Gene Therapy
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