Traits

Traits linked to COL9A3

collagen type IX alpha 3 chain

The Human Phenotype Ontology links 66 traits to COL9A3, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of limbs

Trait	How often it is seen
Dropped arches	Always
Internal tibial torsion	Always
Pes valgus	Always
Limb undergrowth	Often (30–79%)
Limited knee straightening	Often (30–79%)
Reduced arm span	Often (30–79%)
Abnormal kneecap	Sometimes (5–29%)
Abnormal radial epiphysis morphology	Sometimes (5–29%)
Abnormality of end part of the elbow bone	Sometimes (5–29%)
Abnormality of the ankle	Sometimes (5–29%)
Abnormality of the end part of the foot bone	Sometimes (5–29%)
Abnormality of the knee	Sometimes (5–29%)
Bilateral coxa valga	Sometimes (5–29%)
Broad femoral neck	Sometimes (5–29%)
Coxa vara	Sometimes (5–29%)
Fragmentation of end part of the long bone of hand	Sometimes (5–29%)
Knock knees	Sometimes (5–29%)
Limited elbow extension	Sometimes (5–29%)
Outward bow-leggedness	Sometimes (5–29%)
Radially deviated wrists	Sometimes (5–29%)
Ulnar deviated club hands	Sometimes (5–29%)
Abnormality of the hip joint	Not recorded
Shortened long bone of hand	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Abnormal development of end part of bone	Very often (80–99%)
Abnormal shape of end part of bone	Very often (80–99%)
Double-Jointed	Often (30–79%)
Hip joint pain	Often (30–79%)
Irregular vertebral endplates	Often (30–79%)
Knee pain	Often (30–79%)
Degenerative joint disease	Sometimes (5–29%)
Flattened vertebrae	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Spondyloepiphyseal dysplasia	Sometimes (5–29%)
Muscle tissue disease	Rarely (1–4%)
Muscle weakness	Rarely (1–4%)
Delayed maturation of end part of long bone	Not recorded
Irregular end part of long bone	Not recorded
Proximal neurogenic muscle weakness	Not recorded
Small end part of bone	Not recorded

Abnormality of the eye

Trait	How often it is seen
Astigmatism	Always
Severe near sightedness	Very often (80–99%)
Abnormal vitreous humor morphology	Often (30–79%)
Close sighted	Often (30–79%)
Clouding of the lens of the eye	Often (30–79%)
Drooping upper eyelid	Often (30–79%)
Moderate myopia	Often (30–79%)
Vitreoretinopathy	Often (30–79%)
Lattice retinal degeneration	Sometimes (5–29%)
Retinal detachment	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Flat face	Very often (80–99%)
Depressed nasal bridge	Often (30–79%)
Downward slanting of the opening between the eyelids	Often (30–79%)
Little lower jaw	Often (30–79%)
Midface retrusion	Often (30–79%)
Zygomatic flattening	Often (30–79%)
High palate	Sometimes (5–29%)
Cleft palate	Rarely (1–4%)

Abnormality of the nervous system

Trait	How often it is seen
Intellectual disability	Always
Waddling gait	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Joint pain	Often (30–79%)
Postexertional symptom exacerbation	Often (30–79%)

Growth abnormality

Trait	How often it is seen
Short stature	Sometimes (5–29%)
Mild short stature	Not recorded

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Not recorded
Mildly elevated creatine kinase	Not recorded

Abnormality of the ear

Trait	How often it is seen
Sensorineural hearing impairment	Always

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 COL9A3 and how often each is seen. Find out more at hpo.jax.org.

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