Genetic Variations of anatomy might hold the key to one of the mysteries of lung disease. We have often heard musings about the way some people’s lungs seem to tolerate smoking. And it seems, some people’s lungs simply do not cope with the habit. Let’s look at a quick story of Genetic Variation:
Why Can Some People Smoke 50 Years without Paying the Price of COPD?
Meet Mr. and Mrs. “B,” who prove that genetic variations exist in lung and airway structure.
- On the one hand, Mr. B has smoked 45 years and barely ever coughs for any reason.
- On the other hand, Mrs. B smoked for only four years. And she ended up with stage 3 COPD–six years after she quit the habit.
- It does not seem fair. How could a person indulge in smoking for half a lifetime, and never show a trace of COPD? Likewise, why would another person who barely smoked, face early retirement and death from COPD?
New Study Reveals Mysteries of Genetic Variations in Air-way Trees
Early this year a research study might have revealed the genetics explaining the anatomy and disparity in the two smokers. And much more. Finally, the reason for the mystery might reside in the actual structure of the lungs and airways. And genetic variations are the key to that structure.
Do you remember first seeing the trachea and the upside-down tree of branching bronchi? If you did, you probably saw it in the anatomy diagram of your biology book? Well, it might surprise you. But, everyone does not have the identical “upside down tree structure to their trachea and bronchi. You may remember that the bronchi branch into smaller and smaller “y’s.” Because of Genetic Variations, some people have a missing branch. And other people might have an extra branch.
Genetic Variations in the Famous Upside Down Tree
So–surprise–everyone’s little “upside down tree” is not perfect. Now here is the revelation. “Researchers have discovered that genetic variations in the anatomy of the lungs. These variations could serve as indicators to help identify people with:”
- Low, but stable, lung function early in life.
- And those who are particularly at risk for chronic obstructive pulmonary disease (COPD) because of a smoke-induced decline in lung function.
New Genetic Studies Point to Newly Understood Genetic Causes of COPD and Other Lung Diseases
The Journal Proceedings of the National Academy of Sciences published the study in January 2018. Funded by the National Heart, Lung and Blood Institute (NHLBI,) the researchers began with a few premises.
1. They pre-supposed that “Cigarette smoking has long been the most common cause of COPD…”
2. They added statistical proof that not all smokers develop the conditions of COPD…
3. They also noted that many non-smokers develop COPD…
4. The team proceeded to study the airway trees as well as the genetics of patients. The researchers found a clue to the mysteries. They discovered that the variations in airway trees are linked to a higher prevalence of COPD in many older American patients.
By the way, they did not have to dissect the patients’ airway trees in order to determine their differences. They utilized a simple CT Scan to discover the variance in airway
The Mysteries Solve Old Questions with New Theories
James Kiley, M.D., director of the NHLBI Division of Lung Diseases, stated, “This work raises many interesting questions for researchers.”
Not All Seniors Have Dreadful Lung Diseases. Your heredity is a factor.
He explained, “Understanding precisely why these genes influence the development of COPD may lead to entirely new and more effective ways of preventing or treating this disease.”
Likewise, he added, “This novel study suggests that a CT scan can be used to measure airway structure…” (CT scans are widely available.) Dr. Kiley continued. It could “predict who is at higher risk for smoke-induced lung injury.”
A Little Backstory on these Airway Trees and the COPD Disease
You might need to know a few background characteristics of COPD.
1. COPD is a progressive disease. The most insidious feature of it is difficulty in breathing.
2. COPD is the fourth leading cause of Death in the USA.
3. 16 million people have COPD, but Millions more are undiagnosed.
Surprises in the Mysteries of Structure and Genetics
Scientists have long believed that COPD only occurred in late life. Previously, they also believed patients contracted COPD simply from long exposure to cigarette smoke. (And/or air pollution.) They thought that these outside influences pushed lung function into decline and chronic illness. However, recent studies like the one detailed above have demonstrated that many older adults had low lung function from the beginning of their lives.
Genetics Studies Reveal Variations in Lung Branches
Their lung function was always weak. And the function declined at a normal rate for them, due to aging and genetics. The very structure of the airway trees predisposed them. Sometimes the smoking exacerbated it. And sometimes, the predisposition was genetic.
Mysteries Revealed by Leader of the Study
1. The study’s first author, Benjamin M. Smith, M.D. M.S. an assistant professor at Columbia University Medical Center led this study. He stated, “In the current study, we found that central airway branches of the lungs, which are believed to form early in life, do not follow the textbook pattern in one-quarter of the adult population…”
2. He added, “and these non-textbook variations in airway branches are associated with higher COPD prevalence among older adults.”
3. He explained, “Interestingly, one of the airway branch variants was associated with COPD among smokers and non-smokers. The other was associated with COPD, but only among smokers.”
The Good News Behind the Mysteries
Portions of the Population May Have Greater, Fewer or Less Developed Airway Branches.
The study explained, “These airway tree variations are identifiable on low-dose screening lung CT scans, which are currently indicated clinically for lung cancer screening in older patients with a history of heavy smoking in the prior 15 years.
Naturally, research scientists must do more studies before they can utilize CT scans to identify airway variants in clinical practice. However, the researchers are quite hopeful that the future study of airway trees can confirm preventive or therapeutic interventions.
These discoveries prove once again that research-oriented and patient care studies go hand and glove. With hopeful eyes, we at Florida Lung, Asthma and Sleep Specialists, look to the future as science penetrates the mysteries of disease, anatomy, and genetics.