A simple asthma blood test may be in the works

Up until now, there hasn't been any easy way to diagnose asthma, but a new discovery may help scientists create a blood test for the breathing condition.

Penn State researchers previously showed that chemicals in the lungs and blood called microRNAs -- miRNAs for short -- which may regulate proteins involved in allergic inflammation, could be used as asthma biomarkers. But the researchers didn't know if people with asthma have different miRNA compared with people who have other related conditions, so they took a deeper look.

With the help of 79 study participants -- some with asthma, some with just nasal allergies and no asthma, and some with no nasal allergies or asthma -- the scientists examined miRNAs in the blood of each person.

They found different expression patterns among the three groups, and honed in on 30 miRNAs that are involved in allergies and asthma. They identified patterns that helped them predict with high accuracy whether or not a person had asthma.

The study findings, published in The Journal of Allergy and Clinical Immunology, bring them closer to developing a blood test for asthma, said study author Dr. Faoud Ishmael.

Ishmael, an associate professor of medicine and biochemistry and molecular biology at Penn State College of Medicine, told CBS News, "Asthma is a very common disease, but it can actually be very difficult to diagnose, as we don't have great diagnostic tests and there are no blood tests that can help us to diagnose the disease."

Ishmael said one way doctors diagnose asthma is by using lung function tests that rely on measuring how fast a person can blow air out of the lungs.

"But these often are not able to make the diagnosis," he said, and the lung function test can often be difficult for children and some adults to perform.

Complicating matters even more is that scientists now know that asthma is "heterogeneous," Ishmael explained. "What causes it in one person -- and in return what medications it responds to -- can be very different in another person. As a result, there is a great need to find tests that can both diagnose asthma, as well as characterize the disease further."

He said, "We think that the blood test that we have developed can do both of these. The test is based on the fact that we have molecules that circulate in the blood called microRNAs. There are at least 150 types of these molecules that can be easily detected in the blood, and they resemble DNA, the building blocks that make up our genes. The levels of specific microRNAs go up or down depending on different diseases that may be present in our body, and so they can serve as a kind of fingerprint to diagnose different diseases."

There are basically different patterns of miRNAs and they can be high or low in different diseases, Ishmael said.

"We found that there is a characteristic pattern or 'fingerprint' that is seen in asthma. In essence, there are a panel of microRNAs that increased or decreased in the blood that allow us to differentiate asthmatics from non-asthmatics with over 90 percent accuracy," he said.

Better understanding of miRNA patterns could eventually help doctors better tailor the right medications for a patient's type of asthma, Ishmael said.

"As the technology to measure levels of microRNAs in the blood is sensitive, reproducible, and cheap, we hope that these findings can be translated into a diagnostic test," he said.

The researchers are currently working on validating the tests in a larger number of people with asthma, a condition that affects some 25 million Americas.

"Our hope is to have a diagnostic test in the next five years or so," Ishmael said.