It is often characterized by blood and sputum eosinophilia or increased biomarkers associated with eosinophilic activation such as FeNO, serum periostin, serum eosinophil cationic protein (S-ECP), and urinary eosinophil-derived neurotoxin (U- EDN). This evidence concerns the gene RNASE3 and Increased total eosinophil count.