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


Reviewed April 2010

What is the official name of the CTDP1 gene?

The official name of this gene is “CTD phosphatase subunit 1.”

CTDP1 is the gene's official symbol. The CTDP1 gene is also known by other names, listed below.

What is the normal function of the CTDP1 gene?

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.

Does the CTDP1 gene share characteristics with other genes?

The CTDP1 gene belongs to a family of genes called serine/threonine phosphatases (serine/threonine phosphatases).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the CTDP1 gene related to health conditions?

congenital cataracts, facial dysmorphism, and neuropathy - caused by mutations in the CTDP1 gene

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.

Where is the CTDP1 gene located?

Cytogenetic Location: 18q23

Molecular Location on chromosome 18: base pairs 79,679,801 to 79,754,510

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

The CTDP1 gene is located on the long (q) arm of chromosome 18 at position 23.

The CTDP1 gene is located on the long (q) arm of chromosome 18 at position 23.

More precisely, the CTDP1 gene is located from base pair 79,679,801 to base pair 79,754,510 on chromosome 18.

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

Where can I find additional information about CTDP1?

You and your healthcare professional may find the following resources about CTDP1 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 CTDP1 gene or gene products?

  • 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

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

What glossary definitions help with understanding CTDP1?

cell ; congenital ; domain ; enzyme ; gene ; mutation ; neuropathy ; phosphatase ; protein ; RNA ; RNA polymerase ; serine ; subunit ; synthesis ; transcription ; transcription factor

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Gene Review: Congenital Cataracts, Facial Dysmorphism, and Neuropathy (
  • Kalaydjieva L. Congenital cataracts-facial dysmorphism-neuropathy. Orphanet J Rare Dis. 2006 Aug 29;1:32. Review. (
  • Majello B, Napolitano G. Control of RNA polymerase II activity by dedicated CTD kinases and phosphatases. Front Biosci. 2001 Oct 1;6:D1358-68. Review. (
  • NCBI Gene (
  • 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. (
  • 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, Lochmüller H, Müllner-Eidenböck A, Merlini L, Neumann L, Bürger 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. Epub 2003 Sep 21. (


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: April 2010
Published: February 8, 2016