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KRT3 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

KRT3 gene

The KRT3 gene provides instructions for making keratin 3, a protein that maintains the structural integrity of the corneal epithelium in the eye.

Normal Function

The KRT3 gene provides instructions for making a protein called keratin 3. 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 3 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 3 protein partners with another keratin protein, keratin 12, to form molecules known as intermediate filaments. These filaments assemble into strong networks that provide strength and resilience to the corneal epithelium.

Health Conditions Related to Genetic Changes

Meesmann corneal dystrophy

At least three mutations in the KRT3 gene have been found to cause Meesmann corneal dystrophy, an eye disease characterized by the formation of tiny cysts in the corneal epithelium.

All of the identified KRT3 gene mutations associated with Meesmann corneal dystrophy change single protein building blocks (amino acids) in the keratin 3 protein. These changes occur in a region of the protein that is critical for the formation and stability of intermediate filaments. The altered keratin 3 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.

Other Names for This Gene

  • 65 kDa cytokeratin
  • CK-3
  • CK3
  • cytokeratin 3
  • cytokeratin-3
  • K2C3_HUMAN
  • K3
  • keratin 3, type II
  • keratin, type II cytoskeletal 3
  • type-II keratin Kb3

Frequently Asked Questions

Patients often notice a mild gritty or foreign‑body sensation, occasional blurred vision, or the appearance of tiny gray or white spots on the cornea that may become more noticeable with age. If these symptoms arise, a slit‑lamp examination can detect the characteristic cysts in the corneal epithelium.
The diagnosis begins with a detailed eye history and a slit‑lamp examination. Ophthalmologists may use in‑situ confocal microscopy to visualize the cysts and, if needed, order genetic testing that sequences the KRT3 gene to confirm pathogenic mutations.
There is no cure that stops cyst development. Management focuses on symptom relief: preservative‑free artificial tears, avoiding eye trauma, and wearing protective eyewear. In severe cases, a corneal transplant may be considered, but it does not address the underlying genetic defect.
Yes, it is inherited in an autosomal dominant pattern. A parent with the mutation has a 50 % chance of passing it to each child. Genetic counseling is recommended for affected families to discuss testing and family planning options.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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