Both blood eosinophils and eosinophil cationic protein (ECP) have been identified in patients with bronchiolitis, cystic fibrosis and asthmatic children.[34,35] Arron et al. [36] reported that using a threshold of 270 eosinophils μl–1 of blood, showed a positive and negative predictive value of 79% and 91%, respectively, for predicting sputum eosinophilia > 3% in adults with asthma. The gene discussed is RNASE3; the disease is cystic fibrosis.