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Genetics Home Reference: your guide to understanding genetic conditions
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PROS1

Reviewed October 2009

What is the official name of the PROS1 gene?

The official name of this gene is “protein S (alpha).”

PROS1 is the gene's official symbol. The PROS1 gene is also known by other names, listed below.

What is the normal function of the PROS1 gene?

The PROS1 gene provides instructions for making a protein called protein S that is important for controlling blood clotting. By itself, protein S cannot carry out the chemical reactions necessary for regulating the formation of blood clots. Instead, protein S attaches to certain enzymes and enhances their function. On the basis of this action, protein S is called a cofactor.

Protein S is made chiefly by cells in the liver. The protein circulates in the bloodstream in two forms; it is either attached (bound) to a specific protein or occurs by itself in a free form. Both forms of proteins S can act as cofactors; however, bound protein S is less effective than the free form. Protein S is a cofactor for an enzyme called activated protein C (APC). APC turns off (inactivates) the blood clotting proteins known as factor Va and factor VIIIa. Protein S also helps an enzyme known as tissue factor pathway inhibitor (TFPI) block the activity of another clotting protein, factor Xa.

How are changes in the PROS1 gene related to health conditions?

protein S deficiency - caused by mutations in the PROS1 gene

More than 220 mutations in the PROS1 gene have been found to cause protein S deficiency. Most of these mutations change single protein building blocks (amino acids) in protein S, which disrupts its ability to act as a cofactor. Protein S deficiency can be divided into three types based on the mutation in the PROS1 gene.

Protein S deficiency type I is caused by PROS1 gene mutations that result in reduced levels of protein S. Affected individuals do not have enough protein S to control blood clotting, which causes the increased risk for abnormal blood clots in protein S deficiency.

Mutations that cause protein S deficiency type II result in the production of an altered protein S with reduced activity. Individuals with this form of the condition have normal levels of protein S, but the protein is not able to interact with other molecules involved in blood clotting. If protein S does not function properly, abnormal blood clots may form.

Protein S deficiency type III occurs when there is a low amount of free protein S, but the overall amount of protein S is normal. Because free protein S is a more effective cofactor than bound protein S, reduced levels of free protein S can disrupt the inactivation of blood clotting proteins.

Where is the PROS1 gene located?

Cytogenetic Location: 3q11.2

Molecular Location on chromosome 3: base pairs 93,873,036 to 93,974,089

The PROS1 gene is located on the long (q) arm of chromosome 3 at position 11.2.

The PROS1 gene is located on the long (q) arm of chromosome 3 at position 11.2.

More precisely, the PROS1 gene is located from base pair 93,873,036 to base pair 93,974,089 on chromosome 3.

See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.

Where can I find additional information about PROS1?

You and your healthcare professional may find the following resources about PROS1 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 PROS1 gene or gene products?

  • PROS
  • PROS_HUMAN
  • protein Sa
  • protein S, alpha
  • protein S, alpha preproprotein
  • PS21
  • PS22
  • PS23
  • PS24
  • PS25
  • PSA
  • vitamin K-dependent plasma protein S

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What glossary definitions help with understanding PROS1?

acids ; blood clotting ; clotting ; cofactor ; deficiency ; enzyme ; gene ; mutation ; protein ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).

References

  • Castoldi E, Hackeng TM. Regulation of coagulation by protein S. Curr Opin Hematol. 2008 Sep;15(5):529-36. doi: 10.1097/MOH.0b013e328309ec97. Review. (http://www.ncbi.nlm.nih.gov/pubmed/18695379?dopt=Abstract)
  • García de Frutos P, Fuentes-Prior P, Hurtado B, Sala N. Molecular basis of protein S deficiency. Thromb Haemost. 2007 Sep;98(3):543-56. Review. (http://www.ncbi.nlm.nih.gov/pubmed/17849042?dopt=Abstract)
  • Hackeng TM, Maurissen LF, Castoldi E, Rosing J. Regulation of TFPI function by protein S. J Thromb Haemost. 2009 Jul;7 Suppl 1:165-8. doi: 10.1111/j.1538-7836.2009.03363.x. Review. (http://www.ncbi.nlm.nih.gov/pubmed/19630792?dopt=Abstract)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/5627)
  • OMIM: PROTEIN S (http://omim.org/entry/176880)
  • Pintao MC, Garcia AA, Borgel D, Alhenc-Gelas M, Spek CA, de Visser MC, Gandrille S, Reitsma PH. Gross deletions/duplications in PROS1 are relatively common in point mutation-negative hereditary protein S deficiency. Hum Genet. 2009 Sep;126(3):449-56. doi: 10.1007/s00439-009-0687-9. Epub 2009 May 23. (http://www.ncbi.nlm.nih.gov/pubmed/19466456?dopt=Abstract)
  • Ten Kate MK, Platteel M, Mulder R, Terpstra P, Nicolaes GA, Reitsma PH, van der Steege G, van der Meer J. PROS1 analysis in 87 pedigrees with hereditary protein S deficiency demonstrates striking genotype-phenotype associations. Hum Mutat. 2008 Jul;29(7):939-47. doi: 10.1002/humu.20687. (http://www.ncbi.nlm.nih.gov/pubmed/18435454?dopt=Abstract)
  • ten Kate MK, van der Meer J. Protein S deficiency: a clinical perspective. Haemophilia. 2008 Nov;14(6):1222-8. doi: 10.1111/j.1365-2516.2008.01775.x. Epub 2008 May 7. Review. (http://www.ncbi.nlm.nih.gov/pubmed/18479427?dopt=Abstract)

 

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.

 
Reviewed: October 2009
Published: July 7, 2014