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

GJ gene family

Reviewed February 2009

What are the GJ genes?

Genes in the GJ gene family provide instructions for producing proteins called connexins. Connexins are one part (subunit) of a structure called a connexon that is found within cell membranes. Six connexins make up one connexon. Connexons allow for cell-to-cell communication by joining with connexons of other cells to form a channel. Many channels clustered together form a gap junction. Gap junctions speed the transport of nutrients, charged particles (ions), and other small molecules that carry signals between cells. Communication through gap junctions helps regulate many different processes, including heart function, cell growth and specialization, and development before birth.

There are 21 known genes in the human GJ gene family. The genes in this family are designated by the letters GJ and an additional letter and number specific to that particular gene, for example GJB2.

Changes in GJ genes are associated with disorders that affect different parts of the body. Specifically, mutations in the GJB1 gene cause one form of Charcot-Marie-Tooth disease, an inherited condition that affects the nervous system. Additionally, mutations in the GJA1 gene cause oculodentodigital dysplasia, a condition that primarily affects the development of the eyes, teeth, and fingers. Other conditions associated with mutations in the GJ genes include deafness, clouding of the lens of the eyes (cataracts), and various skin disorders.

Which genes are included in the GJ gene family?

The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families ( and their member genes.

Genetics Home Reference summarizes the normal function and health implications of these members of the GJ gene family: GJA1, GJB1, GJB2, GJB3, GJB4, and GJB6.

What conditions are related to genes in the GJ gene family?

Genetics Home Reference includes these conditions related to genes in the GJ gene family:

  • Bart-Pumphrey syndrome
  • Charcot-Marie-Tooth disease
  • Clouston syndrome
  • critical congenital heart disease
  • erythrokeratodermia variabilis et progressiva
  • heterotaxy syndrome
  • hystrix-like ichthyosis with deafness
  • keratitis-ichthyosis-deafness syndrome
  • nonsyndromic hearing loss
  • oculodentodigital dysplasia
  • palmoplantar keratoderma with deafness
  • Vohwinkel syndrome

Where can I find additional information about the GJ gene family?

You may find the following resources about the GJ gene family helpful.

  • Molecular Cell Biology (fourth edition, 2000): Structure of Gap Junctions (figure) ( (U.S. National Library of Medicine)
  • Molecular Biology of the Cell (fourth edition, 2002): Gap Junctions (figure) ( (U.S. National Library of Medicine)
  • Molecular Biology of the Cell (fourth edition, 2002): Gap Junctions Allow Small Molecules to Pass Directly from Cell to Cell ( (U.S. National Library of Medicine)
  • Madame Curie Bioscience Database: Connexins ( (U.S. National Library of Medicine)
  • Biochemistry (fifth edition, 2002): Gap Junctions Allow Ions and Small Molecules to Flow between Communicating Cells ( (U.S. National Library of Medicine)

What glossary definitions help with understanding the GJ gene family?

cell ; channel ; charged particles ; dysplasia ; gap junction proteins ; gap junctions ; gene ; inherited ; ions ; nervous system ; protein ; subunit

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


These sources were used to develop the Genetics Home Reference summary for the GJ gene family.

  • Rabionet R, López-Bigas N, Arbonès ML, Estivill X. Connexin mutations in hearing loss, dermatological and neurological disorders. Trends Mol Med. 2002 May;8(5):205-12. Review. (
  • Richard G. Connexins: a connection with the skin. Exp Dermatol. 2000 Apr;9(2):77-96. Review. (
  • Wei CJ, Xu X, Lo CW. Connexins and cell signaling in development and disease. Annu Rev Cell Dev Biol. 2004;20:811-38. Review. (
  • Meşe G, Richard G, White TW. Gap junctions: basic structure and function. J Invest Dermatol. 2007 Nov;127(11):2516-24. Review. (
  • Sáez JC, Retamal MA, Basilio D, Bukauskas FF, Bennett MV. Connexin-based gap junction hemichannels: gating mechanisms. Biochim Biophys Acta. 2005 Jun 10;1711(2):215-24. Epub 2005 Mar 2. Review. (
  • Laird DW. Life cycle of connexins in health and disease. Biochem J. 2006 Mar 15;394(Pt 3):527-43. Review. (


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: February 2009
Published: February 8, 2016