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Why Do Some Smokers Have Healthy Lungs?

photo credit: Despite smoking their entire lives, some people seem to be protected against lung disease. gdvcom/Shutterstock

Smoking cigarettes, as we all know, carries with it all sorts of risks, from heart disease to mouth cancers. Yet there are still some people who, despite having smoked for their entire life, appear to have healthy lungs. Now researchers think they may have cracked the mystery of how they seem to be protected from the ravages of more than 7,000 chemicalsthey inhale.

The scientists were looking to see if there was a genetic basis behind why some people getchronic obstructive pulmonary disease (COPD), and some don’t. COPD is the name given for a collection of diseases which cause people to have breathlessness, chest infections and persistent coughs, and is due to a narrowing of the airways, causing airflow obstruction. It is the third leading cause of death globally and causes an estimated 135,000 deaths annually in the United States alone.

By studying over 50,000 people, who ranged from heavy smokers to those who had never smoked in their life, the researchers were able to show that lung function and health in both smokers and non-smokers were associated with a handful of independent genetic variations. According to the researchers, these seem to be affecting how the lungs grow and repair themselves, and are the first example of how variations in our genes may affect lung health. Exactly how these genes do this is not yet known.

“These findings, taken together with previous findings, will help define pathways underlying predisposition to development of COPD and smoking behaviours,” explain the authors of the study, published in The Lancet Respiratory Medicine. “A full understanding of the biological mechanisms underlying these genetic associations will improve our understanding of the pathophysiology of COPD and smoking behaviour, and potentially give rise to novel therapeutic strategies for the management of airway disease and prevention of nicotine addiction.”

The researchers, from both the University of Leicester and the University of Nottingham, analyzed the mountains of data held by the U.K. Biobank project. This is a massive resource that collected information on 500,000 volunteers from across the country who submitted blood, urine and saliva samples, gave detailed information about themselves and their lifestyle, underwent measurements, and agreed to have their health followed.

Using this data alongside a new genetic analysis technique which allowed the team to look at a vast number of differences in the participants DNA very quickly, they were able to measure over 800,000 genetic variations. They then compared lung health and self-reported smoking behavior to both common and rare genetic variations. Of these, they found six genetic variations were associated with lung health.

One of these variations is found on Chromosome 17, where the researchers found that the number of copies of a duplicated sequence on the KANSL1 gene was associated with healthier lungs in both heavy smokers and non-smokers. While these genetic variations are associated with better lung health, the reason why is still a little murky.

Understanding how our genes might be impacting lung health could help in developing new treatments for sufferers, although the best way to protect against COPD is to simply either not to smoke in the first place, or stop if you already do.

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