The presence of reduced surfactant and elevated levels of proteins such as surfactant protein A (SP-A) and surfactant protein D (SP-D) indicate alveolar dysfunction, while the presence of collagen types I and III and elevated levels of Transforming Growth Factor β (TGF-β) have been associated with pulmonary fibrosis in severe cases [34,35]. Here, SFTPD is linked to pulmonary fibrosis.