Pulmonary surfactant-associated proteins promote alveolar stability by lowering the surface tension at the air- liquid interface in the peripheral air spaces. SP-B increases the collapse pressure of palmitic acid to nearly 70 millinewtons per meter. Defects in SFTPB are the cause of pulmonary surfactant metabolism dysfunction type 1 (SMDP1); also called pulmonary alveolar proteinosis due to surfactant protein B deficiency. A rare lung disorder due to impaired surfactant homeostasis. It is characterized by alveolar filling with floccular material that stains positive using the periodic acid- Schiff method and is derived from surfactant phospholipids and protein components. Excessive lipoproteins accumulation in the alveoli results in severe respiratory distress. Genetic variations in SFTPB are a cause of susceptibility to respiratory distress syndrome in premature infants (RDS). RDS is a lung disease affecting usually premature newborn infants. It is characterized by deficient gas exchange, diffuse atelectasis, high-permeability lung edema and fibrin-rich alveolar deposits called 'hyaline membranes'. A variation Ile to Thr at position 131 influences the association between specific alleles of SFTPA1 and respiratory distress syndrome in premature infants. Note: This description may include information from UniProtKB.