SFTPD and newborn respiratory distress syndrome: However, the current clinical surfactants used for surfactant replacement therapy (SRT) to treat infant respiratory distress syndrome (RDS), a common cause of morbidity and mortality in preterm neonates characterized by pulmonary immaturity and lack of PS, lack the hydrophilic collectins SP-A and SP-D (Johansson and Curstedt, 2019; Hentschel et al., 2020).