Traits

Traits linked to KCNJ2

potassium inwardly rectifying channel subfamily J member 2

The Human Phenotype Ontology links 94 traits to KCNJ2, by body system: features seen in people with one of the gene's rare conditions.

KCNJ2

Abnormality of head or neck

Trait	How often it is seen
Dental crowding	Always
Little lower jaw	Always
Thin red part of the upper lip	Always
Abnormal dentition	Often (30–79%)
Abnormal facial shape	Often (30–79%)
Abnormality of dental color	Sometimes (5–29%)
Broad forehead	Sometimes (5–29%)
Bulbous nose	Sometimes (5–29%)
Decreased size of maxilla	Sometimes (5–29%)
Delayed loss of baby teeth	Sometimes (5–29%)
Facial asymmetry	Sometimes (5–29%)
Failure of development of more than six teeth	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Scaphocephaly	Sometimes (5–29%)
Short opening between the eyelids	Sometimes (5–29%)
Triangular face	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)
Abnormally small head	Not recorded
Antegonial notching of mandible	Not recorded
Cleft palate	Not recorded
Delayed eruption of permanent teeth	Not recorded
Increased size of frontal sinus	Not recorded
Narrow opening between the eyelids	Not recorded
Pit in front of the ear	Not recorded
Short mandibular rami	Not recorded
Thin dental enamel	Not recorded
Zygomatic flattening	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Shortened QT interval	Always
Slow heartbeats	Very often (80–99%)
Fainting spell	Often (30–79%)
Palpitations	Often (30–79%)
Paroxysmal atrial fibrillation	Often (30–79%)
Prolonged QT interval	Often (30–79%)
Prolonged QTc interval	Often (30–79%)
Quivering upper heart chambers resulting in irregular heartbeat	Often (30–79%)
Ventricular arrhythmia	Often (30–79%)
Abnormal T-wave	Sometimes (5–29%)
Bidirectional ventricular ectopy	Sometimes (5–29%)
Extra heart beat	Sometimes (5–29%)
Heart attack	Sometimes (5–29%)
Interruption of electrical communication between upper and lower chambers of heart	Sometimes (5–29%)
Mildly reduced left ventricular ejection fraction	Sometimes (5–29%)
Permanent atrial fibrillation	Sometimes (5–29%)
Polymorphic and polytopic ventricular extrasystoles	Sometimes (5–29%)
Polymorphic ventricular tachycardia	Sometimes (5–29%)
Presyncope	Sometimes (5–29%)
Prominent U wave	Sometimes (5–29%)
Stretched and thinned heart muscle	Sometimes (5–29%)
Sudden cardiac death	Sometimes (5–29%)
Torsade de pointes	Sometimes (5–29%)
Ventricular fibrillation	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Small hand	Always
Curvature of little finger	Often (30–79%)
Small finger	Often (30–79%)
Clinodactyly of the 5th toe	Sometimes (5–29%)
Short foot	Sometimes (5–29%)
Webbed 2nd and 3rd toes	Sometimes (5–29%)
Fused toes	Not recorded
Short finger bones	Not recorded
Short fingers or toes	Not recorded
Short long bone of foot	Not recorded
Short palm	Not recorded
Shortened long bone of hand	Not recorded
Winged shoulder blade	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Periodic paralysis	Always
Periodic hypokalemic paresis	Often (30–79%)
Epilepsy	Sometimes (5–29%)
Neurodevelopmental delay	Sometimes (5–29%)
Periodic hyperkalemic paralysis	Sometimes (5–29%)
Specific learning disability	Sometimes (5–29%)
Depression	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Muscle weakness	Always
Episodic flaccid weakness	Very often (80–99%)
Double-Jointed	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Delayed bone maturation	Not recorded
Slender long bone	Not recorded

Constitutional symptom

Trait	How often it is seen
Chest pain	Often (30–79%)
Decreased ability to exercise	Often (30–79%)
Fatigue	Often (30–79%)

Growth abnormality

Trait	How often it is seen
Short stature	Often (30–79%)
Growth delay	Sometimes (5–29%)
Growth abnormality	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Thromboembolic stroke	Sometimes (5–29%)
Thromboembolism	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Dizziness	Often (30–79%)
Low-set ears	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Overactive thyroid	Often (30–79%)
Elevated plasma aldosterone	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Abnormal function of filtrating structures in kidney	Rarely (1–4%)
Small kidneys	Rarely (1–4%)

Abnormality of the eye

Trait	How often it is seen
Wide-set eyes	Always

Abnormality of the respiratory system

Trait	How often it is seen
Breathing difficulty	Often (30–79%)

Laboratory abnormality

Trait	How often it is seen
Low blood potassium levels	Not recorded

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 KCNJ2 and how often each is seen. Find out more at hpo.jax.org.

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