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


Reviewed August 2012

What is the official name of the KRT12 gene?

The official name of this gene is “keratin 12, type I.”

KRT12 is the gene's official symbol. The KRT12 gene is also known by other names, listed below.

What is the normal function of the KRT12 gene?

The KRT12 gene provides instructions for making a protein called keratin 12. Keratins are a group of tough, fibrous proteins that form the structural framework of epithelial cells, which are cells that line the surfaces and cavities of the body. Keratin 12 is produced in a tissue on the surface of the eye called the corneal epithelium. This tissue forms the outermost layer of the cornea, which is the clear front covering of the eye. The corneal epithelium acts as a barrier to help prevent foreign materials, such as dust and bacteria, from entering the eye.

The keratin 12 protein partners with another keratin protein, keratin 3, to form molecules known as intermediate filaments. These filaments assemble into strong networks that provide strength and resilience to the corneal epithelium.

Does the KRT12 gene share characteristics with other genes?

The KRT12 gene belongs to a family of genes called KRT (keratins).

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 KRT12 gene related to health conditions?

Meesmann corneal dystrophy - caused by mutations in the KRT12 gene

At least 20 mutations in the KRT12 gene have been found to cause Meesmann corneal dystrophy, an eye disease characterized by the formation of tiny cysts in the corneal epithelium.

Almost all of the KRT12 gene mutations associated with Meesmann corneal dystrophy change single protein building blocks (amino acids) in the keratin 12 protein. These changes occur in regions of the protein that are critical for the formation and stability of intermediate filaments. The altered keratin 12 protein interferes with the assembly of intermediate filaments, weakening the structural framework of the corneal epithelium. As a result, this outer layer of the cornea is abnormally fragile and develops the cysts that characterize Meesmann corneal dystrophy. The cysts likely contain clumps of abnormal keratin proteins and other cellular debris. When the cysts break open (rupture), they cause eye irritation, increased sensitivity to light (photophobia), and related symptoms.

Where is the KRT12 gene located?

Cytogenetic Location: 17q12

Molecular Location on chromosome 17: base pairs 40,861,178 to 40,867,210

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

The KRT12 gene is located on the long (q) arm of chromosome 17 at position 12.

The KRT12 gene is located on the long (q) arm of chromosome 17 at position 12.

More precisely, the KRT12 gene is located from base pair 40,861,178 to base pair 40,867,210 on chromosome 17.

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

Where can I find additional information about KRT12?

You and your healthcare professional may find the following resources about KRT12 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 KRT12 gene or gene products?

  • CK-12
  • cytokeratin-12
  • K1C12_HUMAN
  • K12
  • keratin-12
  • keratin 12
  • keratin, type I cytoskeletal 12

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

What glossary definitions help with understanding KRT12?

acids ; bacteria ; cornea ; cysts ; cytokeratin ; epithelial ; epithelium ; gene ; intermediate filaments ; keratin ; motif ; photophobia ; protein ; resilience ; rupture ; sensitivity ; tissue

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


  • Corden LD, Swensson O, Swensson B, Smith FJ, Rochels R, Uitto J, McLEAN WH. Molecular genetics of Meesmann's corneal dystrophy: ancestral and novel mutations in keratin 12 (K12) and complete sequence of the human KRT12 gene. Exp Eye Res. 2000 Jan;70(1):41-9. (
  • Irvine AD, Corden LD, Swensson O, Swensson B, Moore JE, Frazer DG, Smith FJ, Knowlton RG, Christophers E, Rochels R, Uitto J, McLean WH. Mutations in cornea-specific keratin K3 or K12 genes cause Meesmann's corneal dystrophy. Nat Genet. 1997 Jun;16(2):184-7. (
  • NCBI Gene (
  • Nishida K, Adachi W, Shimizu-Matsumoto A, Kinoshita S, Mizuno K, Matsubara K, Okubo K. A gene expression profile of human corneal epithelium and the isolation of human keratin 12 cDNA. Invest Ophthalmol Vis Sci. 1996 Aug;37(9):1800-9. (
  • Nishida K, Honma Y, Dota A, Kawasaki S, Adachi W, Nakamura T, Quantock AJ, Hosotani H, Yamamoto S, Okada M, Shimomura Y, Kinoshita S. Isolation and chromosomal localization of a cornea-specific human keratin 12 gene and detection of four mutations in Meesmann corneal epithelial dystrophy. Am J Hum Genet. 1997 Dec;61(6):1268-75. (


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: August 2012
Published: February 8, 2016