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Reviewed March 2014

What is the official name of the TBXAS1 gene?

The official name of this gene is “thromboxane A synthase 1.”

TBXAS1 is the gene's official symbol. The TBXAS1 gene is also known by other names, listed below.

What is the normal function of the TBXAS1 gene?

The TBXAS1 gene provides instructions for making an enzyme called thromboxane A synthase 1. This enzyme acts as part of a chemical pathway called the arachidonic acid cascade. Through this multistep pathway, a molecule called arachidonic acid is processed to produce several molecules with diverse functions in the body. As part of this pathway, thromboxane A synthase 1 converts a molecule called prostaglandin H2 into another molecule called thromboxane A2. Thromboxane A2 is involved in normal blood clotting (hemostasis), playing critical roles in the narrowing of blood vessels (vasoconstriction) to slow blood flow and the clumping (aggregation) of blood cell fragments called platelets at the site of an injury.

Studies suggest that the activity of thromboxane A synthase 1 may also be important for bone remodeling, which is a normal process in which old bone is removed and new bone is created to replace it, and for the production of red blood cells in bone marrow.

Does the TBXAS1 gene share characteristics with other genes?

The TBXAS1 gene belongs to a family of genes called CYP (cytochrome P450s).


How are changes in the TBXAS1 gene related to health conditions?

Ghosal hematodiaphyseal dysplasia - caused by mutations in the TBXAS1 gene

At least four mutations in the TBXAS1 gene have been found to cause Ghosal hematodiaphyseal dysplasia. This condition is characterized by abnormally thick bones and a shortage of red blood cells (anemia) caused by scarring (fibrosis) of the bone marrow.

Each of the known mutations changes a single protein building block (amino acid) in thromboxane A synthase 1, which severely reduces the activity of the enzyme. A shortage of this enzyme's activity prevents the conversion of prostaglandin H2 to thromboxane A2. As a result, cells have more prostaglandin H2 than usual. Prostaglandin H2 is converted into several related molecules, including prostaglandin E2, which is thought to be involved in bone remodeling and in controlling the growth of immature red blood cells. Researchers speculate that an increase in prostaglandin E2 levels resulting from excess prostaglandin H2 contributes to the bone abnormalities and anemia that occur in people with Ghosal hematodiaphyseal dysplasia. However, the exact mechanism by which a lack of thromboxane A synthase 1 activity leads to the particular features of this condition is still unclear.

A shortage of thromboxane A synthase 1 activity also reduces the level of thromboxane A2 in cells. Although this molecule plays a critical role in hemostasis, people with Ghosal hematodiaphyseal dysplasia do not appear to have problems with blood clotting. Researchers suspect that other molecules involved in vasoconstriction and platelet aggregation may be able to compensate for the lack of thromboxane A2 in these individuals.

Where is the TBXAS1 gene located?

Cytogenetic Location: 7q34-q35

Molecular Location on chromosome 7: base pairs 139,778,248 to 140,020,325


The TBXAS1 gene is located on the long (q) arm of chromosome 7 between positions 34 and 35.


More precisely, the TBXAS1 gene is located from base pair 139,778,248 to base pair 140,020,325 on chromosome 7.


Where can I find additional information about TBXAS1?

You and your healthcare professional may find the following resources about TBXAS1 helpful.


What other names do people use for the TBXAS1 gene or gene products?

  • BDPLT14
  • CYP5
  • CYP5A1
  • cytochrome P450 5A1
  • cytochrome P450, family 5, subfamily A, polypeptide 1
  • platelet, cytochrome P450, subfamily V
  • THAS
  • thromboxane-A synthase
  • thromboxane A synthase 1 (platelet)
  • thromboxane A synthase 1 (platelet, cytochrome P450, family 5, subfamily A)
  • TS
  • TXAS
  • TXA synthase
  • TXS


What glossary definitions help with understanding TBXAS1?

amino acid ; anemia ; blood clotting ; bone marrow ; bone remodeling ; cell ; clotting ; cytochrome P450 ; dysplasia ; enzyme ; fibrosis ; gene ; hemostasis ; injury ; molecule ; platelets ; prostaglandin ; protein



  • Geneviève D, Proulle V, Isidor B, Bellais S, Serre V, Djouadi F, Picard C, Vignon-Savoye C, Bader-Meunier B, Blanche S, de Vernejoul MC, Legeai-Mallet L, Fischer AM, Le Merrer M, Dreyfus M, Gaussem P, Munnich A, Cormier-Daire V. Thromboxane synthase mutations in an increased bone density disorder (Ghosal syndrome). Nat Genet. 2008 Mar;40(3):284-6. doi: 10.1038/ng.2007.66. Epub 2008 Feb 10. (
  • Isidor B, Dagoneau N, Huber C, Genevieve D, Bader-Meunier B, Blanche S, Picard C, De Vernejoul MC, Munnich A, Le Merrer M, Cormier-Daire V. A gene responsible for Ghosal hemato-diaphyseal dysplasia maps to chromosome 7q33-34. Hum Genet. 2007 Apr;121(2):269-73. Epub 2007 Jan 3. (
  • Miyata A, Yokoyama C, Ihara H, Bandoh S, Takeda O, Takahashi E, Tanabe T. Characterization of the human gene (TBXAS1) encoding thromboxane synthase. Eur J Biochem. 1994 Sep 1;224(2):273-9. (
  • NCBI Gene (



Reviewed: March 2014
Published: February 1, 2016