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JAG1 gene

jagged canonical Notch ligand 1

Normal Function

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.

Health Conditions Related to Genetic Changes

Alagille syndrome

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.

More About This Health Condition

Critical congenital heart disease

MedlinePlus Genetics provides information about Critical congenital heart disease

More About This Health Condition


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.

Other Names for This Gene

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

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


  • 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. doi: 10.1093/hmg/ddm222. Epub 2007 Aug 24. Citation on PubMed
  • 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. doi: 10.1002/1098-1004(200102)17:23.0.CO;2-T. Citation on PubMed
  • 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. Citation on PubMed or Free article on PubMed Central
  • 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. Citation on PubMed
  • Kamath BM, Bason L, Piccoli DA, Krantz ID, Spinner NB. Consequences of JAG1 mutations. J Med Genet. 2003 Dec;40(12):891-5. doi: 10.1136/jmg.40.12.891. Citation on PubMed or Free article on PubMed Central
  • Kim BJ, Fulton AB. The genetics and ocular findings of Alagille syndrome. Semin Ophthalmol. 2007 Oct-Dec;22(4):205-10. doi: 10.1080/08820530701745108. Citation on PubMed
  • 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. doi: 10.1086/374386. Epub 2003 Mar 14. Citation on PubMed or Free article on PubMed Central
  • 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. doi: 10.1161/01.cir.0000037221.45902.69. Citation on PubMed
  • 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. doi: 10.1093/hmg/10.4.405. Citation on PubMed
  • Piccoli DA, Spinner NB. Alagille syndrome and the Jagged1 gene. Semin Liver Dis. 2001 Nov;21(4):525-34. doi: 10.1055/s-2001-19036. Citation on PubMed
  • 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. doi: 10.1002/1098-1004(2001)17:13.0.CO;2-T. Citation on PubMed
  • Spinner NB, Loomes KM, Krantz ID, Gilbert MA. Alagille Syndrome. 2000 May 19 [updated 2024 Jan 4]. 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

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