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The official name of this gene is “surfactant protein B.”
SFTPB is the gene's official symbol. The SFTPB gene is also known by other names, listed below.
The SFTPB gene provides instructions for making a protein called surfactant protein-B (SP-B). This protein is one of four proteins (each produced from a different gene) in surfactant, a mixture of certain fats (called phospholipids) and proteins that lines the lung tissue and makes breathing easy. Without normal surfactant, the tissue surrounding the air sacs in the lungs (the alveoli) sticks together after exhalation (because of a force called surface tension), causing the alveoli to collapse. As a result, filling the lungs with air on each breath becomes very difficult, and the delivery of oxygen to the body is impaired. Surfactant lowers surface tension, easing breathing and avoiding lung collapse. The SP-B protein helps spread the surfactant across the surface of the lung tissue, aiding in the surface tension-lowering property of surfactant.
The phospholipids and proteins that make up surfactant are packaged in cellular structures known as lamellar bodies, which are found in specialized lung cells. The surfactant proteins must go through several processing steps to mature and become functional; some of these steps occur in lamellar bodies. The SP-B protein plays a role in the formation of lamellar bodies and, thus, affects the processing of a surfactant protein called surfactant protein-C (SP-C).
More than 30 mutations in the SFTPB gene that cause surfactant dysfunction have been identified. Surfactant dysfunction due to SFTPB gene mutations (often called SP-B deficiency) causes severe, often fatal breathing problems in newborns. These mutations lead to partial or complete loss of mature SP-B, resulting in abnormal composition of surfactant and decreased surfactant function. In addition, lamellar body formation is impaired. The lack of normal lamellar bodies leads to abnormal processing of SP-C, resulting in a reduction of mature SP-C and a buildup of unprocessed forms of SP-C. The loss of functional surfactant raises surface tension in the alveoli, causing difficulty breathing and collapse of the lungs. The combination of SP-B and SP-C dysfunction may explain why the signs and symptoms of SP-B deficiency are so severe.
Cytogenetic Location: 2p12-p11.2
Molecular Location on chromosome 2: base pairs 85,657,316 to 85,668,740
The SFTPB gene is located on the short (p) arm of chromosome 2 between positions 12 and 11.2.
More precisely, the SFTPB gene is located from base pair 85,657,316 to base pair 85,668,740 on chromosome 2.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about SFTPB helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
alveoli ; deficiency ; gene ; oxygen ; Phe ; phospholipids ; protein ; pulmonary ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.