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


Reviewed May 2015

What is the official name of the AMELX gene?

The official name of this gene is “amelogenin, X-linked.”

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

What is the normal function of the AMELX gene?

The AMELX gene provides instructions for making a protein called amelogenin, which is essential for normal tooth development. Amelogenin is involved in the formation of enamel, which is the hard, white material that forms the protective outer layer of each tooth. Enamel is composed mainly of mineral crystals. These microscopic crystals are arranged in organized bundles that give enamel its strength and durability. Although the exact function of amelogenin is not well understood, it appears to separate and support the crystals as they grow. Amelogenin is removed from the developing crystals when it is no longer needed, leaving mature enamel that contains very little protein.

One copy of the amelogenin gene is located on each of the sex chromosomes (the X and Y chromosomes). The AMELX gene, which is located on the X chromosome, makes almost all of the body's amelogenin. The copy of the amelogenin gene on the Y chromosome, AMELY, makes very little amelogenin and is not needed for enamel formation.

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

amelogenesis imperfecta - caused by mutations in the AMELX gene

At least 23 mutations in the AMELX gene have been identified in people with an X-linked form of a disorder of tooth development called amelogenesis imperfecta. (X-linked disorders are caused by mutations in genes on the X chromosome.) Some AMELX gene mutations lead to the production of an abnormal version of the amelogenin protein that can interfere with the formation and organization of enamel crystals. Other AMELX gene mutations prevent one copy of the gene from producing any amelogenin protein at all. Enamel cannot form properly without an adequate amount of amelogenin.

Males have a single copy of the X chromosome in each cell. Males who inherit an altered copy of the AMELX gene have very little amelogenin and develop almost no enamel to cover and protect their teeth. (The normal AMELY gene on the Y chromosome does not provide enough amelogenin to compensate.) Females have two copies of the X chromosome in each cell. Females who inherit one altered copy of the AMELX gene are less severely affected than males because they have a normal copy of the gene on the other X chromosome to produce amelogenin. Their tooth enamel may have structural defects such as a distinctive pattern of vertical grooves.

Where is the AMELX gene located?

Cytogenetic Location: Xp22.31-p22.1

Molecular Location on the X chromosome: base pairs 11,292,578 to 11,300,761

The AMELX gene is located on the short (p) arm of the X chromosome between positions 22.31 and 22.1.

The AMELX gene is located on the short (p) arm of the X chromosome between positions 22.31 and 22.1.

More precisely, the AMELX gene is located from base pair 11,292,578 to base pair 11,300,761 on the X chromosome.

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

Where can I find additional information about AMELX?

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

  • AIH1
  • ALGN
  • amelogenin (amelogenesis imperfecta 1, X-linked)
  • AMG
  • AMGL
  • AMGX

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

What glossary definitions help with understanding AMELX?

amelogenesis ; cell ; chromosome ; enamel ; gene ; hypoplasia ; inherit ; mineral ; protein ; sex chromosomes

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


  • Hu JC, Chan HC, Simmer SG, Seymen F, Richardson AS, Hu Y, Milkovich RN, Estrella NM, Yildirim M, Bayram M, Chen CF, Simmer JP. Amelogenesis imperfecta in two families with defined AMELX deletions in ARHGAP6. PLoS One. 2012;7(12):e52052. doi: 10.1371/journal.pone.0052052. Epub 2012 Dec 14. (
  • Kida M, Sakiyama Y, Matsuda A, Takabayashi S, Ochi H, Sekiguchi H, Minamitake S, Ariga T. A novel missense mutation (p.P52R) in amelogenin gene causing X-linked amelogenesis imperfecta. J Dent Res. 2007 Jan;86(1):69-72. (
  • Lakshminarayanan R, Bromley KM, Lei YP, Snead ML, Moradian-Oldak J. Perturbed amelogenin secondary structure leads to uncontrolled aggregation in amelogenesis imperfecta mutant proteins. J Biol Chem. 2010 Dec 24;285(52):40593-603. doi: 10.1074/jbc.M110.131136. Epub 2010 Oct 7. (
  • Margolis HC, Beniash E, Fowler CE. Role of macromolecular assembly of enamel matrix proteins in enamel formation. J Dent Res. 2006 Sep;85(9):775-93. Review. (
  • NCBI Gene (
  • Wright JT, Li Y, Suggs C, Kuehl MA, Kulkarni AB, Gibson CW. The role of amelogenin during enamel-crystallite growth and organization in vivo. Eur J Oral Sci. 2011 Dec;119 Suppl 1:65-9. doi: 10.1111/j.1600-0722.2011.00883.x. (
  • Wright JT, Torain M, Long K, Seow K, Crawford P, Aldred MJ, Hart PS, Hart TC. Amelogenesis imperfecta: genotype-phenotype studies in 71 families. Cells Tissues Organs. 2011;194(2-4):279-83. doi: 10.1159/000324339. Epub 2011 May 19. (
  • Wright JT. The molecular etiologies and associated phenotypes of amelogenesis imperfecta. Am J Med Genet A. 2006 Dec 1;140(23):2547-55. 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: May 2015
Published: November 23, 2015