Serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 6, also Corticosteroid-Binding Globulin or Transcortin
Structure of corticosteroid-binding globulin in complex with cortisol.
Alt. symbols CBG
Entrez 866
HUGO 1540
OMIM 122500
RefSeq NM_001750
UniProt P08185
Other data
Locus Chr. 14 q32.1

Transcortin, also corticosteroid-binding globulin or CBG, is officially called serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 6.

It is an alpha-globulin.



Transcortin binds several steroid hormones:

  • Cortisol. Approximately 75% of the cortisol in circulation is bound to this plasma protein. (The rest is bound to serum albumin.) The cortisol is thought to be biologically active only when it is not bound to transcortin.


Transcortin is produced by the liver and is regulated by estrogens. Therefore, plasma transcortin levels increase during pregnancy, and are decreased in cirrhosis.


Mutations in this gene are rare. To date only five cases have been reported.[1] All cases have been associated with generalised pain and fatigue. This mechanism for these symptoms is not known. This condition must be distinguished from secondary hypocortisolism. Exogenous hydrocortisone does not appear to improve the fatigue.


  1. ^ Torpy DJ, Lundgren BA, Ho JT, Lewis JG, Scott HS, Mericq V (2011) CBG Santiago: a Novel CBG Mutation. J Clin Endocrinol Metab

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