Second-hand smoke worsens lung function in people with cystic fibrosis, especially those with a specific gene, researchers said on Tuesday.
Researchers at Johns Hopkins University School of Medicine in Baltimore showed how genetic and environmental factors can interact to harm lung function in cystic fibrosis patients, said Dr. Garry Cutting who worked on the study.

     Cystic fibrosis is an inherited chronic disease that affects the lungs and digestive system of about 30,000 children and adults in the United States, according to the Cystic Fibrosis Foundation.

     It causes thick, sticky mucus to build up, leading to life-threatening lung infections and major digestion problems.

     The researchers studied 812 people with the disease whose average age was 19 of whom 188 were exposed to second-hand cigarette smoke at home.

     Lung function in those exposed to second-hand smoke was reduced by about 10 percent compared to those not exposed, the researchers found. Lung function was determined by how much air a person could breathe out in the first second of expiration.

     The researchers then looked at lung function in those who also had a specific version of a gene called TGFbeta1 that affects the severity of this disease and asthma.

     Having this gene variant doubled the negative effects of second-hand smoke on lung function, the researchers wrote in the Journal of the American Medical Association.

     The research did not look at lung function in people with cystic fibrosis who are active smokers, Cutting said in a telephone interview.

     "There really haven't been that many patients with cystic fibrosis who have had active smoking. But there have been a number of anecdotal reports that show that it's absolutely disastrous for them to actively smoke," Cutting said.

     被動吸煙使囊腫纖維化的人的肺功能變壞，尤其是那些有特異基因的人。科研人員在周二的時候這樣說。

     巴爾的摩的約翰霍普金斯大學醫學院的科研人員演示了基因和環境因素如何相互影響囊腫纖維化患者的肺功能。正在從事這項研究的高利卡特博士這樣說。

   囊腫纖維化是一種遺傳性的慢性疾病，根據囊腫纖維化基金的結果，它影響著美國大約3萬的兒童和成人的肺和消化系統。

   它產生厚重粘稠的粘液產生堵塞作用，導致危及生命的肺部感染和嚴重的消化道問題。

   科研人員研究了812例患有這種疾病的患者，他們的平均年齡19歲。其中有188例患者有家庭的被動吸煙史。

  研究人員發現，和那些沒有被動吸煙的患者相比，那些被動吸煙的患者肺功能大約下降了10%。肺功能的判定用第一秒呼氣量來衡量。

   然后研究人員又觀察了那些有特異TGFbeta1基因型的患者的肺功能。TGFbeta1能夠影響這種疾病及哮喘性疾病的嚴重性。

   擁有這種基因變異體對肺功能的負面影響是被動吸煙對肺功能影響的二倍。研究人員將這一點寫進了在美國醫學協會的雜志上。

    研究人員沒有觀察那些主動吸煙的囊腫纖維化患者的肺功能。卡特在電話接見的時候說。

     沒有太多的囊腫纖維化的患者是主動吸煙的。但是有一些有趣的報道表明，主動吸煙對他們來說是絕對有損害的。卡特說。