Half of children with asthma will continue to suffer from the respiratory disorder as adults, and a new genetic test could reveal who remains at risk past childhood.
About one in 11 children suffers from asthma, according to the Centers for Disease Control (CDC), and although half will eventually grow out of the condition, a recent CDC survey found that medical costs of asthma and its complications add up to about $56 billion each year. Improved treatment of those most likely to live with their condition longer term, say experts, could help to lower some of these costs, which include treating complications and mismanaged symptoms.
Researchers report in the journal Lancet Respiratory Medicine that a new genetic test may be able to predict a child’s risk of having asthma into adulthood, and therefore help doctors figure out which children might need more intensive care in childhood to potentially lower their risk of longer term symptoms.
The new study piggy backs on so-called genome-wide association (GWAS) studies, which compare those affected by asthma to those who are not to isolate specific genetic markers that could be associated with the disease. In the 40-year long study, Duke University researchers developed a genetic risk score that was based on 15 variants gleaned from previous GWAS, and looked at how these scores matched up to physical symptoms of asthma over time among 880 participants. The genetic score reflected only individual participant’s asthma risk, independent of family history.
The kids with higher scores, which meant they were more likely to possess more of the genetic markers linked to asthma, were also more likely to have asthma symptoms as adults, based on a 38 year follow-up. Those with the higher genetic risk also tended to miss school or work or be hospitalized for their symptoms more often than those with lower genetic scores.
Family history of asthma, the researchers say, did not appear to correlate with a higher genetic risk of the disease; many of the participants with high genetic risk had no family history of asthma, and conversely, people with a strong family history of the disease showed low genetic risk. That suggests that many of the cases were caused by environmental factors such as exposure to pollution or other irritants that have been linked to respiratory problems.
That means that doctors may need to expand the criteria they use to assess asthma risk to include measures such as genetic factors, which may be more predictive of future disease than family history. “What we are discovering in GWAS and doing molecular studies of asthma, is giving us new information over and above the old fashioned way we used to evaluate the genetic risk for asthma and still are in the clinic, which is to take family histories,” says study author Dan Belsky, a postdoctoral Fellow at Duke University. “I think that we are seeing more and more genomic medicine as time goes on. It is really coming into play in cancer medicine. It is not yet there in the treatment of asthma, but I think it will be coming. This study shows some of what may be possible.”
Belsky says scientists are far from knowing which genetic factors are directly responsible for causing asthma, but GWAS are a first step toward narrowing down the field of likely candidates. Most experts believe that for conditions such as asthma, multiple genes may contribute to the disease’s symptoms, so panels such as the one discovered in the current study could help to triage patients and ultimately guide them toward the most effective treatments — both in childhood and in adulthood.