Genetic disorders of surfactant dysfunction.
Mutations in the genes encoding the surfactant proteins B and C (SP-B and SP-C) and the phospholipid transporter, ABCA3, are associated with respiratory distress and interstitial lung disease in the pediatric population. Expression of these proteins is regulated developmentally, increasing with gestational age, and is critical for pulmonary surfactant function at birth. Pulmonary surfactant is a unique mixture of lipids and proteins that reduces surface tension at the air-liquid interface, preventing collapse of the lung at the end of expiration. SP-B and ABCA3 are required for the normal organization and packaging of surfactant phospholipids into specialized secretory organelles, known as lamellar bodies, while both SP-B and SP-C are important for adsorption of secreted surfactant phospholipids to the alveolar surface. In general, mutations in the SP-B gene SFTPB are associated with fatal respiratory distress in the neonatal period, and mutations in the SP-C gene SFTPC are more commonly associated with interstitial lung disease in older infants, children, and adults. Mutations in the ABCA3 gene are associated with both phenotypes. Despite this general classification, there is considerable overlap in the clinical and histologic characteristics of these genetic disorders. In this review, similarities and differences in the presentation of these disorders with an emphasis on their histochemical and ultrastructural features will be described, along with a brief discussion of surfactant metabolism. Mechanisms involved in the pathogenesis of lung disease caused by mutations in these genes will also be discussed.
Wert
Susan E
SE
Perinatal Institute, Section of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, and the Department of Pediatrics, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA. susan.wert@cchmc.org
Whitsett
Jeffrey A
JA
Nogee
Lawrence M
LM
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000328:Adult; D002675:Child, Preschool; D006801:Humans; D007231:Infant, Newborn; D008171:Lung Diseases / Q000235:genetics* / Q000473:pathology; D037701:Pulmonary Surfactant-Associated Protein B / Q000172:deficiency / Q000235:genetics*; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics*
C441524:ABCA3 protein, human; D018528:ATP-Binding Cassette Transporters; D037701:Pulmonary Surfactant-Associated Protein B; D037721:Pulmonary Surfactant-Associated Protein C