In a new study seven genes linked to asthma have been discovered. For the research genetic variations of 10,365 people with asthma and 16,110 people without the condition was studied. The variants identified showed an association with childhood asthma and some were also associated with later-onset asthma.
Earlier studies have shown that asthma can be hereditary or due to environmental triggers. This study may eventually lead to better ways of preventing or treating asthma, but such developments are likely to take some time.
The study was carried out by the GABRIEL consortium, a collaboration between researchers from institutes across Europe and other countries which attempts to identify the genetic and environmental causes of asthma and was funded by the European Commission, the French Ministry of Research, the Wellcome Trust and Asthma UK. It was published in the peer-reviewed New England Journal of Medicine.
The researcher team examined the genetic sequences at over half-a-million known sites throughout the participants’ DNA to identify any genetic variants that were more or less common in people with asthma than those without it. Study participants were European or of European descent living in Canada, the US or Australia. The team also studied genetic variations associated with levels of a substance called IgE in the participants’ blood. IgE is a protein involved in allergic reactions and is produced by the immune system and is raised in asthmatics.
Results showed that five particular genetic variations with a significant association with asthma. When looking at childhood and later onset asthma separately most of these genetic variations showed a greater association with childhood asthma than later-onset asthma. The individual variations each altered the risk of developing asthma by between 11% and 20%.Changes on chromosome 17 was associated with childhood-onset asthma only. Two of the strongest links here were within the GSDMB and GSDMA genes. Only one variant near the HLA-DR gene had a statistically significant association with levels of the IgE protein in the participants’ blood.
With this identification now researchers could correctly identify only 35% of people who had asthma and 75% of those who did not have asthma. The seven variations were together estimated to account for 38% of cases of childhood asthma. Thus the genetic testing may not be absolutely accurate but may help in drug development say researchers.
Prof Miriam Moffatt of Imperial College London, lead researcher said, “We now know allergies may develop as a result of defects of the lining of the airways in asthma…This does not mean allergies are not important, but it does mean that concentrating therapies only on allergy will not effectively treat the whole disease.”
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