Traits

Traits linked to KRT9

keratin 9

The Human Phenotype Ontology links 18 traits to KRT9, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the integument

Trait	How often it is seen
Hyperkeratosis	Very often (80–99%)
Abnormal fingernails	Often (30–79%)
Knuckle pad	Often (30–79%)
Thickening of upper layer of skin	Often (30–79%)
Abnormal blistering of the skin	Sometimes (5–29%)
Excessive sweating	Sometimes (5–29%)
Hypergranulosis	Sometimes (5–29%)
Localized epidermolytic hyperkeratosis	Not recorded

Abnormality of limbs

Trait	How often it is seen
Thickening of the outer layer of the skin of the palms and soles	Very often (80–99%)
Clubbing of fingers and toes	Often (30–79%)
Diffuse palmoplantar hyperkeratosis	Often (30–79%)
Interphalangeal joint contracture of finger	Often (30–79%)
Palmar hyperkeratosis	Often (30–79%)
Plantar hyperkeratosis	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Impaired temperature sensation	Sometimes (5–29%)
Impaired touch sensation	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Increased circulating IgE concentration	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Permanent flexion of the finger or toe	Sometimes (5–29%)

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to KRT9 and how often each is seen. Find out more at hpo.jax.org.

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