Simple Blood Test Identifies Genetic Cause for COPD

Dec 14, 2015 at 03:28 pm by steve

Christopher Roney, MD examines a COPD patient.

More than 24 million Americans suffer from chronic obstructive pulmonary disease (COPD), which generally is caused by smoking and inhaling secondhand smoke or environmental pollutants. However, a small group of people develop COPD because of a genetic disease.

Alpha-1 antitrypsin deficiency (alpha-1) is an inherited condition that is passed from parents to their children. It affects approximately 100,000 people in the United States, or about three percent of the population with COPD. The alpha-1 protein is made in the liver and normally travels through the bloodstream to help protect the body’s organs, including the lungs, from the harmful effects of other proteins. If the alpha-1 proteins in the liver are not the correct shape, they can get stuck inside liver cells and can’t reach the bloodstream. As a result, not enough of the proteins travel to the lungs to protect them, which increases the risk of lung disease and possible liver disease.

“This deficiency is under recognized and probably unknown to a lot of physicians,” says Christopher Roney, MD, a pulmonologist with Pulmonary & Sleep Associates of Alabama. “It can cause an emphysema-type condition in individuals with no history of smoking or other exposures that typically cause COPD or emphysema.”

Symptoms typically are the same as with COPD, with slight differences. “These patients often present with a cough, wheezing, shortness of breath and chest tightness. In X-rays, the lungs look extra clear and hyper-ventilated like over-inflated balloons,” Roney says. “In people with smoking-related COPD, emphysema typically is upper-lobe predominant. In alpha-1, we see lower lobe emphysema.”

When patients with respiratory symptoms are referred to Roney, he tests pulmonary function for evidence of air flow disorders that indicate COPD. If the clinical situation fits, he screens them for alpha-1.

“If newly diagnosed patients are young or have minimal risk factors for COPD such has smoking, family history, or toxic exposures, I test them for alpha-1,” Roney says. “It’s a simple finger-prick blood test that can identify the alpha-1 enzyme level. The test also looks for genes associated with the enzyme deficiency. If these are present, along with a low enzyme level, they have the disease.”

In a small percentage of these patients, alpha-1 can also affect the liver. “If the liver enzyme is misshapen and can’t exit the liver, it can build up and cause liver damage such as cirrhosis or hepatitis and can increase the risk of liver cancer over time. Rarely, patients can develop a skin condition called panniculitis which is characterized by hardened skin with painful lumps and patches,” he says. “However, the biggest risk is the development of progressive lung disease which causes increasing damage and increased morbidity and mortality over time. Patients need to make sure any siblings and children are tested to see if they also have the deficiency.”

Augmentation therapy is used to treat alpha-1 with a serum made with antitrypsin collected from human donors. The drug is infused once a week to provide patients with the protective enzyme. Researchers are studying an aerosol version of this therapy as well as therapies that will help misshapen alpha-1 proteins move from the liver into the bloodstream. “The goal is to prevent the progression of the lung disease so the patients’ conditions don’t worsen,” Roney says. “Regrettably, the therapy doesn’t treat the COPD condition. We just don’t want it to progress and cause the patient to die prematurely.”

These patients, many of whom don’t smoke, will experience the same type of decline as an individual who smokes three packs a day if the condition is not diagnosed and treated. “The enzyme therapy will help slow the progression, but if someone with alpha-1 smokes, it is imperative that they quit. Smoking is the biggest risk to these patients,” Roney says. “It accelerates the loss of lung function over time and increases the risk of developing significant lung disease. If these patients still smoke, that’s probably the worst thing they can do if they have alpha-1 deficiency.”

Roney wants to increase awareness of this genetic disease among physicians. “I think the main thing is to be aware that this problem exists. Test kits are available from the companies that produce the augmentation drugs and are free for patients who need to be screened,” he says. “If a physician sees an individual with COPD at a relatively young age with unexplained liver disease, no smoking history and no other risk factors for COPD, test them. Refer them to a specialist who is familiar with the disease so they can receive therapy and be followed. The best thing is to catch these patients as soon as possible to prevent progression of lung disease.”




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