Of interest, in proven chronic pneumonitis of infancy (CPI), desquamative interstitial pneumonitis and children with familial unclear RDS in the mature neonate, and the diagnostic exclusion of mutations in SFTPB, SFTPC and ABCA3, no major deviations from normal surfactant composition were observed, suggesting the presence of causes outside the surfactant system but resulting in severe alveolar tissue disintegration (Fig. 5, S5 Fig). Here, SFTPB is linked to Interstitial pneumonitis.