Simultaneously elevated nitric oxide and serum-eosinophil cationic protein have also been linked to asthma exacerbations.50 Some biomarkers such as immunoglobulin E (IgE), sputum or peripheral blood eosinophil count and FENO have also been suggested as helpful when choosing treatment and assessing the prognosis of COPD,51 identifying COPD patients with possible synchronous asthma. This evidence concerns the gene IGHE and chronic obstructive pulmonary disease.