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GJB4 gene

gap junction protein beta 4

Normal Function

The GJB4 gene provides instructions for making a protein called gap junction beta 4, more commonly known as connexin 30.3. This protein is part of the connexin family, a group of proteins that form channels called gap junctions on the surface of cells. Gap junctions open and close to regulate the flow of nutrients, charged atoms (ions), and other signaling molecules from one cell to another. They are essential for direct communication between neighboring cells.

Connexin 30.3 is found in several different tissues, including the outermost layer of the skin (the epidermis). This protein appears to play a role in the growth and maturation of epidermal cells.

Health Conditions Related to Genetic Changes

Erythrokeratodermia variabilis et progressiva

At least eight GJB4 gene mutations have been identified in people with erythrokeratodermia variabilis et progressiva (EKVP), a skin disorder characterized by areas of hyperkeratosis, which is abnormally thickened skin, and temporarily reddened patches called erythematous areas. Each of these mutations changes a single protein building block (amino acid) in connexin 30.3. Studies suggest that the abnormal protein can build up in a cell structure called the endoplasmic reticulum (ER), triggering a harmful process known as ER stress. Researchers suspect that ER stress damages cells in the epidermis and leads to their premature death. The mechanisms by which epidermal damage and cell death contribute to hyperkeratosis at erythematous areas are poorly understood.

More About This Health Condition

Other Names for This Gene

  • connexin 30.3
  • connexin-30.3
  • CX30.3
  • EKV
  • gap junction beta-4 protein
  • gap junction protein, beta 4, 30.3kDa

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Macari F, Landau M, Cousin P, Mevorah B, Brenner S, Panizzon R, Schorderet DF, Hohl D, Huber M. Mutation in the gene for connexin 30.3 in a family with erythrokeratodermia variabilis. Am J Hum Genet. 2000 Nov;67(5):1296-301. doi: 10.1016/S0002-9297(07)62957-7. Epub 2000 Oct 3. Citation on PubMed or Free article on PubMed Central
  • Richard G, Brown N, Rouan F, Van der Schroeff JG, Bijlsma E, Eichenfield LF, Sybert VP, Greer KE, Hogan P, Campanelli C, Compton JG, Bale SJ, DiGiovanna JJ, Uitto J. Genetic heterogeneity in erythrokeratodermia variabilis: novel mutations in the connexin gene GJB4 (Cx30.3) and genotype-phenotype correlations. J Invest Dermatol. 2003 Apr;120(4):601-9. doi: 10.1046/j.1523-1747.2003.12080.x. Citation on PubMed
  • Sbidian E, Bousseloua N, Jonard L, Leclerc-Mercier S, Bodemer C, Hadj-Rabia S. Novel mutation in GJB4 gene (connexin 30.3) in a family with erythrokeratodermia variabilis. Acta Derm Venereol. 2013 Mar 27;93(2):193-5. doi: 10.2340/00015555-1436. No abstract available. Citation on PubMed
  • Scott CA, O'Toole EA, Mohungoo MJ, Messenger A, Kelsell DP. Novel and recurrent connexin 30.3 and connexin 31 mutations associated with erythrokeratoderma variabilis. Clin Exp Dermatol. 2011 Jan;36(1):88-90. doi: 10.1111/j.1365-2230.2010.03945.x. Citation on PubMed
  • van Steensel MA, Oranje AP, van der Schroeff JG, Wagner A, van Geel M. The missense mutation G12D in connexin30.3 can cause both erythrokeratodermia variabilis of Mendes da Costa and progressive symmetric erythrokeratodermia of Gottron. Am J Med Genet A. 2009 Feb 15;149A(4):657-61. doi: 10.1002/ajmg.a.32744. Citation on PubMed
  • Yoshikata-Isokawa Y, Itoh M, Nakagawa H. Japanese sporadic case of erythrokeratodermia variabilis caused by the connexin-30.3 (GJB4) mutation: Is Glycine 12 a mutational hotspot in the connexin family? J Dermatol. 2016 Jul;43(7):830-1. doi: 10.1111/1346-8138.13277. Epub 2016 Jan 30. No abstract available. 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.