This might be a limitation because severe asthma has been associated with increased blood eosinophil count, high S-ECP and P-EDN, as well as increased levels of IgE and FENO compared to patients with mild to moderate asthma.39,40 Including also patients with a more prominent inflammation and more pronounced sickness behaviour would increase the variation in the investigated variables and would have increased the power in the analyses. This evidence concerns the gene IGHE and asthma.