Traits

Traits linked to GJA1

gap junction protein alpha 1

The Human Phenotype Ontology links 223 traits to GJA1, by body system: features seen in people with one of the gene's rare conditions.

GJA1

Abnormality of head or neck

Trait	How often it is seen
Decreased width of baby teeth	Always
Delayed eruption of teeth	Always
Enlargement of facial bones	Always
Flat nose	Always
Little lower jaw	Always
Sparse eyebrow	Always
Underdeveloped tissue around nostril	Always
Wide fontanelles	Always
Abnormal tooth enamel	Very often (80–99%)
Abnormality of the nose	Very often (80–99%)
Abnormally small head	Very often (80–99%)
Broad columella	Very often (80–99%)
Cleft palate	Very often (80–99%)
Decreased number of teeth	Very often (80–99%)
Dental cavities	Very often (80–99%)
Depressed nasal bridge	Very often (80–99%)
Early loss of baby teeth	Very often (80–99%)
Enlargement of craniofacial bones	Very often (80–99%)
Narrow nasal bridge	Very often (80–99%)
Sparse eyelashes	Very often (80–99%)
Sparse scalp hair	Very often (80–99%)
Wide nasal bridge	Very often (80–99%)
Big lower jaw	Often (30–79%)
Central cleft upper lip	Often (30–79%)
Corners of eye widely separated	Often (30–79%)
Enlargement of skull bones	Often (30–79%)
High forehead	Often (30–79%)
High palate	Often (30–79%)
Large cranial suture	Often (30–79%)
Nasal tip, upturned	Often (30–79%)
Short nose	Often (30–79%)
Wide gum ridges	Often (30–79%)
Absent eyebrow	Sometimes (5–29%)
Bell's palsy	Sometimes (5–29%)
Eye folds	Sometimes (5–29%)
Non-midline cleft of the upper lip	Sometimes (5–29%)
Taurodontia	Sometimes (5–29%)
Upward slanting of the opening between the eyelids	Sometimes (5–29%)
Abnormal nasopharynx morphology	Not recorded
Absence of a tooth	Not recorded
Bad bite	Not recorded
Big calvaria	Not recorded
Blockage of nose	Not recorded
Bony paranasal bossing	Not recorded
Broad head shape	Not recorded
Cleft upper lip	Not recorded
Coarse facial features	Not recorded
Decreased size of maxilla	Not recorded
Decreased size of teeth	Not recorded
Decreased size of tooth	Not recorded
Decreased volume of lip	Not recorded
Delayed eruption of permanent teeth	Not recorded
Dental crowding	Not recorded
Downward slanting of the opening between the eyelids	Not recorded
Early tooth loss	Not recorded
Frontal bossing	Not recorded
Long nose	Not recorded
Long philtrum	Not recorded
Low hanging columella	Not recorded
Macrodontia of permanent maxillary central incisor	Not recorded
Narrow mouth	Not recorded
Narrow nose	Not recorded
Narrow opening between the eyelids	Not recorded
Short opening between the eyelids	Not recorded
Thin dental enamel	Not recorded

Abnormality of limbs

Trait	How often it is seen
Plantar hyperkeratosis	Always
Thickening of palms and soles	Always
Webbed 4th-5th finger	Always
Abnormality of the wide portion of a long bone	Very often (80–99%)
Curvature of little finger	Very often (80–99%)
Finger syndactyly	Very often (80–99%)
Fused toes	Very often (80–99%)
Joint contracture of the 5th finger	Very often (80–99%)
3-4 finger cutaneous syndactyly	Often (30–79%)
Absent/small middle finger bone of the hand	Often (30–79%)
Curvature of digit	Often (30–79%)
Flexion contracture of finger	Often (30–79%)
Patchy palmoplantar hyperkeratosis	Often (30–79%)
Permanent flexion of the finger	Often (30–79%)
Abnormal shape of shaft of long bone	Sometimes (5–29%)
Extra finger	Sometimes (5–29%)
Extra thumb	Sometimes (5–29%)
Madelung deformity	Sometimes (5–29%)
Short big toe	Sometimes (5–29%)
Short fingers or toes	Sometimes (5–29%)
Short toe	Sometimes (5–29%)
Tapered finger	Sometimes (5–29%)
Absent middle bone of little finger	Not recorded
Club-shaped outermost end of thighbone	Not recorded
Curvature of outermost bone of little finger	Not recorded
Flared wide portion of long bone	Not recorded
Hip dislocation	Not recorded
Metaphyseal dysplasia	Not recorded
Outward turned elbows	Not recorded
Short 5th finger	Not recorded
Short foot	Not recorded
Short middle bone of the little finger	Not recorded
Small hand	Not recorded
Uneven increase in bone density in finger bone	Not recorded
Webbed 2nd, 3rd and 4th toes	Not recorded
Webbed 3rd-4th toes	Not recorded

Abnormality of the integument

Trait	How often it is seen
Atypical nail growth	Always
Brittle hair	Always
Chicken skin	Always
Fine hair	Always
Hair loss	Always
Hypergranulosis	Always
Hyperkeratosis	Always
Orthokeratosis	Always
Patchy darkened skin	Always
Sparse hair	Always
Thickening of upper layer of skin	Always
White discoloration of nails	Always
Abnormal blistering of the skin	Very often (80–99%)
Abnormality of the nail	Very often (80–99%)
Flat, discolored area of skin	Very often (80–99%)
Hyperpigmented skin patches	Very often (80–99%)
Photosensitive skin	Very often (80–99%)
Poor nail formation	Very often (80–99%)
Abnormal fingernails	Often (30–79%)
Abnormality of the hair	Often (30–79%)
Curly hair	Often (30–79%)
Dry skin	Often (30–79%)
Generalized hypotrichosis	Often (30–79%)
Grooved nails	Often (30–79%)
Irregular hyperpigmentation	Often (30–79%)
Sclerodactyly	Often (30–79%)
Slow-growing hair	Often (30–79%)
Absent hair	Sometimes (5–29%)
Cracked skin	Sometimes (5–29%)
Dry hair	Sometimes (5–29%)
Excessive hairiness over body	Sometimes (5–29%)
Poor wound healing	Sometimes (5–29%)
Scaling skin	Sometimes (5–29%)
Skin cancer	Sometimes (5–29%)
Trichorrhexis nodosa	Sometimes (5–29%)
Brittle nails	Not recorded

Abnormality of the eye

Trait	How often it is seen
Abnormally small eyeball	Always
Glaucoma	Always
Uveitis	Always
Wide-set eyes	Always
Cornea of eye less than 10mm in diameter	Very often (80–99%)
Abnormality of the eye	Often (30–79%)
Abnormality of vision	Often (30–79%)
Abnormally close eyes	Often (30–79%)
Close sighted	Often (30–79%)
Clouding of the lens of the eye	Often (30–79%)
Deeply set eye	Often (30–79%)
Optic atrophy	Often (30–79%)
Persistent pupillary membrane	Often (30–79%)
Severe farsightedness	Often (30–79%)
Visual impairment	Often (30–79%)
Abnormality of the iris	Sometimes (5–29%)
Corneal opacity	Sometimes (5–29%)
Cross-eyed	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Yellowish cloudy center of lens	Sometimes (5–29%)
Extreme sensitivity of the eyes to light	Rarely (1–4%)

Abnormality of the nervous system

Trait	How often it is seen
Abnormal gait	Often (30–79%)
Absent/small cerebellum	Often (30–79%)
Ataxia	Often (30–79%)
Delayed motor skills	Often (30–79%)
Delayed speech and language development	Often (30–79%)
Difficulty articulating speech	Often (30–79%)
Epilepsy	Often (30–79%)
Global developmental delay	Often (30–79%)
Increased reflexes	Often (30–79%)
Mild global developmental delay	Often (30–79%)
Abnormal cranial nerve morphology	Sometimes (5–29%)
Intellectual disability	Sometimes (5–29%)
Meningocele	Sometimes (5–29%)
Abnormal cerebral white matter morphology	Not recorded
Hyperactive deep tendon reflexes	Not recorded
Partial paralysis of legs	Not recorded
Tetraparesis	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Harder, denser, fracture-prone bones	Very often (80–99%)
Abnormal cortical bone morphology	Often (30–79%)
Abnormal deposits of calcium in the brain	Often (30–79%)
Abnormal skeletal development	Often (30–79%)
Bone overgrowth	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Muscle weakness	Often (30–79%)
Spastic paraparesis	Often (30–79%)
Abnormal collarbone	Sometimes (5–29%)
Abnormal vertebral body morphology	Sometimes (5–29%)
Abnormality of the chest	Not recorded
Basal ganglia calcification	Not recorded
Broad long bones	Not recorded
Delayed bone maturation	Not recorded
Vertebral hyperostosis	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Palmoplantar erythema	Always
Redness of skin or mucous membrane	Always
Underdeveloped left heart	Very often (80–99%)
Underdeveloped aortic arch	Often (30–79%)
Abnormal cardiovascular system morphology	Sometimes (5–29%)
Abnormal heart rate	Sometimes (5–29%)
An opening in the wall separating the top two chambers of the heart	Sometimes (5–29%)
Blushed cheeks	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Mitral atresia	Sometimes (5–29%)
Mitral stenosis	Sometimes (5–29%)
Patent ductus arteriosus	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Abnormality of the ear	Very often (80–99%)
Abnormally shaped ears	Often (30–79%)
Conductive deafness	Often (30–79%)
Deafness in one ear	Sometimes (5–29%)
Hearing impairment	Sometimes (5–29%)
Prominent ear	Sometimes (5–29%)
Sensorineural hearing impairment	Sometimes (5–29%)
Large earlobe	Not recorded
Low-set ears	Not recorded
Mixed hearing impairment	Not recorded

Growth abnormality

Trait	How often it is seen
Short stature	Very often (80–99%)
Weight loss	Very often (80–99%)
Faltering weight	Often (30–79%)

Abnormality of the genitourinary system

Trait	How often it is seen
Lack of bladder control due to nervous system injury	Often (30–79%)
Abnormality of the testis	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Diabetes mellitus	Often (30–79%)
Low blood sugar	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Abnormality of chromosome segregation	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Digital constriction ring	Often (30–79%)

Abnormality of the digestive system

Trait	How often it is seen
Umbilical hernia	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Skin rash	Very often (80–99%)

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 GJA1 and how often each is seen. Find out more at hpo.jax.org.

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