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CTDP1 gene

CTD phosphatase subunit 1

Normal Function

The CTDP1 gene provides instructions for making a protein called carboxy-terminal domain phosphatase 1. This protein helps regulate the activity of an enzyme called RNA polymerase II. The RNA polymerase II enzyme initiates transcription, which is a key step in using the information carried by genes to direct the production (synthesis) of proteins.

Health Conditions Related to Genetic Changes

Congenital cataracts, facial dysmorphism, and neuropathy

Thus far, everyone with CCFDN has had the same mutation in both copies of the CTDP1 gene in each cell. This mutation, written as IVS6+389C>T, alters the way the gene's instructions are pieced together to produce the carboxy-terminal domain phosphatase 1 protein. The altered instructions introduce a premature stop signal, resulting in an abnormally short, nonfunctional protein that cannot regulate transcription. Defective regulation of the transcription process affects the development and function of many parts of the body. It is not known how nonfunctional carboxy-terminal domain phosphatase 1 protein results in the specific signs and symptoms of CCFDN.

More About This Health Condition

Other Names for This Gene

  • CTD (carboxy-terminal domain, RNA polymerase II, polypeptide A) phosphatase, subunit 1
  • CTD of POLR2A, phosphatase of, subunit 1
  • FCP1
  • RNA polymerase II subunit A C-terminal domain phosphatase
  • RNA polymerase II subunit A C-terminal domain phosphatase isoform FCP1a
  • RNA polymerase II subunit A C-terminal domain phosphatase isoform FCP1b
  • serine phosphatase FCP1a
  • TFIIF-associating CTD phosphatase 1
  • transcription factor IIF-associating CTD phosphatase 1

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Gene and Variant Databases


  • Kalaydjieva L, Chamova T. CTDP1-Related Congenital Cataracts, Facial Dysmorphism, and Neuropathy. 2010 Mar 2 [updated 2022 Oct 13]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Bean LJH, Gripp KW, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from Citation on PubMed
  • Kalaydjieva L. Congenital cataracts-facial dysmorphism-neuropathy. Orphanet J Rare Dis. 2006 Aug 29;1:32. doi: 10.1186/1750-1172-1-32. Citation on PubMed or Free article on PubMed Central
  • Majello B, Napolitano G. Control of RNA polymerase II activity by dedicated CTD kinases and phosphatases. Front Biosci. 2001 Oct 1;6:D1358-68. doi: 10.2741/majello. Citation on PubMed
  • Shabo G, Scheffer H, Cruysberg JR, Lammens M, Pasman JW, Spruit M, Willemsen MA. Congenital cataract facial dysmorphism neuropathy syndrome: a clinically recognizable entity. Pediatr Neurol. 2005 Oct;33(4):277-9. doi: 10.1016/j.pediatrneurol.2005.04.011. Citation on PubMed
  • Varon R, Gooding R, Steglich C, Marns L, Tang H, Angelicheva D, Yong KK, Ambrugger P, Reinhold A, Morar B, Baas F, Kwa M, Tournev I, Guerguelcheva V, Kremensky I, Lochmuller H, Mullner-Eidenbock A, Merlini L, Neumann L, Burger J, Walter M, Swoboda K, Thomas PK, von Moers A, Risch N, Kalaydjieva L. Partial deficiency of the C-terminal-domain phosphatase of RNA polymerase II is associated with congenital cataracts facial dysmorphism neuropathy syndrome. Nat Genet. 2003 Oct;35(2):185-9. doi: 10.1038/ng1243. Epub 2003 Sep 21. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.