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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed July 2012

What is the official name of the SFTPB gene?

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.

What is the normal function of the SFTPB gene?

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).

How are changes in the SFTPB gene related to health conditions?

surfactant dysfunction - caused by mutations in the SFTPB gene

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.

Where is the SFTPB gene located?

Cytogenetic Location: 2p12-p11.2

Molecular Location on chromosome 2: base pairs 85,657,317 to 85,668,741

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The SFTPB gene is located on the short (p) arm of chromosome 2 between positions 12 and 11.2.

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 85,657,317 to base pair 85,668,741 on chromosome 2.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about SFTPB?

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.

What other names do people use for the SFTPB gene or gene products?

  • 6 kDa protein
  • 18 kDa pulmonary-surfactant protein
  • PSP-B
  • pulmonary surfactant-associated protein B
  • pulmonary surfactant-associated proteolipid SPL(Phe)
  • SFTP3
  • SMDP1
  • SP-B

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding SFTPB?

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.


  • NCBI Gene (
  • Nogee LM, Garnier G, Dietz HC, Singer L, Murphy AM, deMello DE, Colten HR. A mutation in the surfactant protein B gene responsible for fatal neonatal respiratory disease in multiple kindreds. J Clin Invest. 1994 Apr;93(4):1860-3. (
  • Nogee LM, Wert SE, Proffit SA, Hull WM, Whitsett JA. Allelic heterogeneity in hereditary surfactant protein B (SP-B) deficiency. Am J Respir Crit Care Med. 2000 Mar;161(3 Pt 1):973-81. (
  • Weaver TE. Synthesis, processing and secretion of surfactant proteins B and C. Biochim Biophys Acta. 1998 Nov 19;1408(2-3):173-9. Review. (


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? ( in the Handbook.

Reviewed: July 2012
Published: February 8, 2016