Asthma is a chronic inflammatory disease of the airways that affects over four million people in Germany. During an asthma attack, typically triggered by pollution or allergies for instance, the lung airways become narrower and clogged with mucus, causing wheezing, coughing, chest tightness and shortness of breath. In its most severe form, asthma can result in the loss of lung function.
The exact cause for asthma is unknown, but people with a family history of asthma, allergies or eczema are more likely to develop asthma at some point in their lives, so it is thought this disease has a strong genetic component. A few studies have identified changes in the DNA of asthmatic patients, but it isn't know whether healthy people carrying these DNA alterations - called single nucleotide polymorphisms (SNPs) - are at higher risk of developing asthma later in life.
In a new study published in Lancet Respiratory Medicine, researchers at Duke University show that children with those asthma-linked SNPs are more likely to develop life-long persistent asthma than those without them. This finding suggests that genetic risk assessments using SNPs could be used to predict a child's risk of developing asthma later in his or her life.
Lead author in the study, Daniel Belsky, and colleagues, looked at the timing of onset, severity and persistence of asthma in 880 individuals since birth and over 38 years of their life. This ongoing study includes results of medical tests for lung function and allergy, records of asthma symptoms, and other information like number of asthma-based hospitalizations. The researchers then sequenced the DNA of these individuals to check for 15 previously identified SNPs linked to a risk of developing asthma, and then used this to calculate an asthma "genetic risk score".
The Duke research team found that boys and girls with higher genetic risk scores (more asthma SNPs) were more likely to develop asthma during the 38 years of the study than those with lower scores. These children also developed asthma earlier in life and were more likely to develop persistent asthma - meaning that the disease was detected before the age of thirteen and produced symptoms up to age 38 (the most recent time point in the study).
Belsky and colleagues concluded that genetic analysis using SNPs may be used to predict whether children with asthma symptoms will grow out of the disease or develop chronic asthma.
The genetic risk scores were also related to the severity of the symptoms. Members with higher risk scores were more likely to develop allergic asthma (the most persistent and severe form) and impaired lung function than those at lower risk.
Because genetic risk score predictions are able to identify different types of asthma they are more on target than predictions made from family history alone. Future studies may include as yet undiscovered SNPs - hundreds of thousands of "flavors" of SNPs instead of only fifteen - and larger numbers of participants.