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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 JAG1 gene?

The official name of this gene is “jagged 1.”

JAG1 is the gene's official symbol. The JAG1 gene is also known by other names, listed below.

What is the normal function of the JAG1 gene?

The JAG1 gene provides instructions for making a protein called Jagged-1, which is involved in an important pathway by which cells can signal to each other. The Jagged-1 protein is inserted into the membranes of certain cells. It connects with other proteins called Notch receptors, which are bound to the membranes of adjacent cells. These proteins fit together like a lock and its key. When a connection is made between the Jagged-1 and Notch proteins, it launches a series of signaling reactions (Notch signaling) affecting cell functions. Notch signaling controls how certain types of cells develop in a growing embryo, especially cells destined to be part of the heart, liver, eyes, ears, and spinal column. The Jagged-1 protein continues to play a role throughout life in the development of new blood cells.

Does the JAG1 gene share characteristics with other genes?

The JAG1 gene belongs to a family of genes called CD (CD molecules).

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 JAG1 gene related to health conditions?

Alagille syndrome - caused by mutations in the JAG1 gene

At least 226 mutations in the JAG1 gene have been identified in people with Alagille syndrome. Most of these mutations result in an abnormally short Jagged-1 protein that is missing the segment that normally spans the cell membrane (the transmembrane domain). Other mutations interfere with proper transport (trafficking) of the protein within the cell, preventing it from reaching the cell membrane. The loss of Jagged-1 protein at the cell membrane precludes its interaction with Notch proteins and prevents cell signaling. The lack of Notch signaling causes errors in development that result in missing or narrowed bile ducts in the liver, heart defects, distinctive facial features, and changes in other parts of the body. People with JAG1 gene mutations may have one or more of these problems. In particular, some affected individuals have a particular combination of heart defects known as tetralogy of Fallot without other signs or symptoms of Alagille syndrome. The type and severity of problems associated with Alagille syndrome may differ even within the same family.

cancers - associated with the JAG1 gene

Increased activity (expression) of the JAG1 gene has been linked to certain cancers, including breast cancer and head and neck tumors. The increased expression of the JAG1 gene may promote the development of new blood vessels that nourish a growing tumor. The altered gene expression may also enhance other cancer-related events such as cell division (proliferation) and the inflammatory response.

Where is the JAG1 gene located?

Cytogenetic Location: 20p12.1-p11.23

Molecular Location on chromosome 20: base pairs 10,637,684 to 10,674,046

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

The JAG1 gene is located on the short (p) arm of chromosome 20 between positions 12.1 and 11.23.

The JAG1 gene is located on the short (p) arm of chromosome 20 between positions 12.1 and 11.23.

More precisely, the JAG1 gene is located from base pair 10,637,684 to base pair 10,674,046 on chromosome 20.

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

Where can I find additional information about JAG1?

You and your healthcare professional may find the following resources about JAG1 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 JAG1 gene or gene products?

  • AGS
  • AHD
  • AWS
  • CD339
  • CD339 antigen
  • HJ1
  • jagged 1 (Alagille syndrome)
  • jagged 1 precursor
  • JAGL1

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

What glossary definitions help with understanding JAG1?

bile ; cancer ; cell ; cell division ; cell membrane ; domain ; embryo ; gene ; gene expression ; ligand ; precursor ; proliferation ; protein ; syndrome ; tetralogy of Fallot ; transmembrane ; tumor

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


  • Boyer-Di Ponio J, Wright-Crosnier C, Groyer-Picard MT, Driancourt C, Beau I, Hadchouel M, Meunier-Rotival M. Biological function of mutant forms of JAGGED1 proteins in Alagille syndrome: inhibitory effect on Notch signaling. Hum Mol Genet. 2007 Nov 15;16(22):2683-92. Epub 2007 Aug 24. (
  • Colliton RP, Bason L, Lu FM, Piccoli DA, Krantz ID, Spinner NB. Mutation analysis of Jagged1 (JAG1) in Alagille syndrome patients. Hum Mutat. 2001 Feb;17(2):151-2. (
  • Dufraine J, Funahashi Y, Kitajewski J. Notch signaling regulates tumor angiogenesis by diverse mechanisms. Oncogene. 2008 Sep 1;27(38):5132-7. doi: 10.1038/onc.2008.227. Review. (
  • Gene Review: Alagille Syndrome (
  • Guarnaccia C, Dhir S, Pintar A, Pongor S. The tetralogy of Fallot-associated G274D mutation impairs folding of the second epidermal growth factor repeat in Jagged-1. FEBS J. 2009 Nov;276(21):6247-57. doi: 10.1111/j.1742-4658.2009.07333.x. Epub 2009 Sep 23. (
  • OMIM: JAGGED 1 (
  • Kamath BM, Bason L, Piccoli DA, Krantz ID, Spinner NB. Consequences of JAG1 mutations. J Med Genet. 2003 Dec;40(12):891-5. (
  • Kim BJ, Fulton AB. The genetics and ocular findings of Alagille syndrome. Semin Ophthalmol. 2007 Oct-Dec;22(4):205-10. Review. (
  • Lu F, Morrissette JJ, Spinner NB. Conditional JAG1 mutation shows the developing heart is more sensitive than developing liver to JAG1 dosage. Am J Hum Genet. 2003 Apr;72(4):1065-70. Epub 2003 Mar 14. (
  • McElhinney DB, Krantz ID, Bason L, Piccoli DA, Emerick KM, Spinner NB, Goldmuntz E. Analysis of cardiovascular phenotype and genotype-phenotype correlation in individuals with a JAG1 mutation and/or Alagille syndrome. Circulation. 2002 Nov 12;106(20):2567-74. (
  • Morrissette JD, Colliton RP, Spinner NB. Defective intracellular transport and processing of JAG1 missense mutations in Alagille syndrome. Hum Mol Genet. 2001 Feb 15;10(4):405-13. (
  • NCBI Gene (
  • Piccoli DA, Spinner NB. Alagille syndrome and the Jagged1 gene. Semin Liver Dis. 2001 Nov;21(4):525-34. Review. (
  • Spinner NB, Colliton RP, Crosnier C, Krantz ID, Hadchouel M, Meunier-Rotival M. Jagged1 mutations in alagille syndrome. Hum Mutat. 2001;17(1):18-33. 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: April 2010
Published: February 1, 2016