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KRT81 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

KRT81 gene

The KRT81 gene provides instructions for making the K81 protein, a type II hair keratin that contributes to the strength and elasticity of the hair shaft.

Normal Function

The KRT81 gene provides instructions for making the type II hair keratin K81 protein (K81). This protein belongs to a group of proteins known as keratins, which are tough, fibrous proteins that form the structural framework of cells that make up the hair, skin, and nails. Each keratin protein partners with another keratin protein to form molecules called intermediate filaments. These filaments assemble into strong networks that provide strength and resiliency to the tissues and protect them from being damaged by everyday physical stresses. The K81 protein is found in cells that make up the inner compartment of the hair shaft known as the cortex, and this protein helps give hair its strength and elasticity.

Health Conditions Related to Genetic Changes

Monilethrix

At least two mutations in the KRT81 gene have been identified in people with monilethrix, a hair condition characterized by strands of hair with a beaded appearance and short, brittle hair that breaks easily. Mutations associated with this condition change a single amino acid in the K81 protein. These changes usually occur in a region of the K81 protein thought to be important in intermediate filament formation. In people with monilethrix, the cortex of the affected hair shaft appears abnormal, though the exact mechanism linking these mutations to the beaded appearance of the hair remains unclear.

Other Names for This Gene

  • ghHb1
  • hair keratin K2.9
  • hard keratin, type II, 1
  • Hb-1
  • HB1
  • hHAKB2-1
  • hHb1
  • keratin 81, type II
  • keratin, hair, basic, 1
  • keratin-81
  • KRT81_HUMAN
  • KRTHB1
  • type II hair keratin Hb1

Genomic Location

The KRT81 gene is found on chromosome 12.

Frequently Asked Questions

Monilethrix typically presents as short, fragile hair that breaks easily, giving the hair a beaded or “saw‑tooth” appearance. The hair may be sparse, especially on the scalp, and can be more prone to split ends and breakage. Hair loss is usually mild to moderate, and the condition often becomes noticeable in early childhood or adolescence. How is a KRT81 mutation confirmed in a patient with suspected monilethrix?::Diagnosis usually starts with a clinical exam of hair texture and pattern. A hair shaft analysis under a microscope can reveal the characteristic beaded structure. Genetic testing—usually a targeted sequencing panel for hair keratin genes—can identify pathogenic variants in KRT81. Can monilethrix be prevented or cured by changing hair care habits?::While the genetic mutation cannot be altered, gentle hair care can reduce breakage. Use mild shampoos, avoid heat styling, minimize tight hairstyles, and apply light conditioners or oils to keep hair hydrated. Regular trims help remove split ends and maintain hair strength. Is monilethrix inherited, and can family members be at risk?::Yes, monilethrix is typically inherited in an autosomal dominant pattern, meaning a single copy of the mutated KRT81 gene can cause the condition. If a parent carries the mutation, there is a 50% chance of passing it to each child. Genetic counseling is recommended for families concerned about inheritance.
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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