Traits

Traits linked to BAG3

BAG cochaperone 3

The Human Phenotype Ontology links 76 traits to BAG3, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the musculoskeletal system

Trait	How often it is seen
Difficulty walking up stairs	Always
Distal lower limb amyotrophy	Always
EMG: myopathic abnormalities	Always
Fatty replacement of skeletal muscle	Always
EMG: neuropathic changes	Very often (80–99%)
Angulated muscle fibers	Often (30–79%)
Axial muscle weakness	Often (30–79%)
Diaphragmatic paralysis	Often (30–79%)
Fiber type grouping	Often (30–79%)
Generalized muscle weakness	Often (30–79%)
Muscle fiber degeneration	Often (30–79%)
Proximal neurogenic muscle weakness	Often (30–79%)
Reduced spine movement	Often (30–79%)
Scoliosis	Often (30–79%)
Thoracic scoliosis	Often (30–79%)
Tired easily	Often (30–79%)
Weakness of outermost muscles	Often (30–79%)
EMG abnormality	Sometimes (5–29%)
Loss of fat tissue in localized area	Sometimes (5–29%)
Muscle spasm	Sometimes (5–29%)
Muscle tissue disease	Sometimes (5–29%)
Diffuse skeletal muscle wasting	Not recorded
Muscular dystrophy	Not recorded
Myofibrillar myopathy	Not recorded

Abnormality of limbs

Trait	How often it is seen
Areflexia of lower limbs	Always
Areflexia of upper limbs	Always
Decreased Achilles reflex	Always
High-arched foot	Always
Hip flexor weakness	Always
Shortening of the achilles tendon	Always
Absent ankle reflexes	Very often (80–99%)
Distal lower limb muscle weakness	Very often (80–99%)
Decreased knee jerk reflex	Often (30–79%)
Foot drop	Often (30–79%)
Lower limb muscle weakness	Often (30–79%)
Pes valgus	Often (30–79%)
Winged shoulder blade	Often (30–79%)
Absent knee jerk reflex	Sometimes (5–29%)
Distal upper limb muscle weakness	Sometimes (5–29%)
Inability to straighten knee	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Abnormal gait	Always
Decreased nerve conduction velocity	Always
Decreased sensory nerve conduction velocity	Always
Decreased touch sensation in extremities	Always
Impaired pain sensation	Always
Impaired vibration sensation in the lower limbs	Always
Peripheral neuropathy	Always
Decreased compound muscle action potential amplitude	Very often (80–99%)
Demyelinating peripheral neuropathy	Often (30–79%)
Numbness	Often (30–79%)
Toe walking	Often (30–79%)
Axonal loss	Not recorded
Decreased reflex response	Not recorded
Decreased sensation in extremities	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Left ventricular systolic dysfunction	Very often (80–99%)
Stretched and thinned heart muscle	Very often (80–99%)
Abnormal heart rate	Often (30–79%)
Cardiac failure	Often (30–79%)
Enlarged and thickened heart muscle	Often (30–79%)
Increased left ventricular end-diastolic volume	Often (30–79%)
Left ventricular hypertrophy	Often (30–79%)
Mitral regurgitation	Often (30–79%)
Restrictive cardiomyopathy	Often (30–79%)
Palpitations	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory function loss	Always
Exertional breathlessness	Often (30–79%)
Orthopnea	Often (30–79%)
Reduced forced vital capacity	Often (30–79%)
Stiff lung or chest wall causing decreased lung volume	Often (30–79%)

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Always
Fluid retention	Often (30–79%)

Abnormality of blood and blood-forming tissues

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

Abnormality of head or neck

Trait	How often it is seen
Bell's palsy	Not recorded

Abnormality of the ear

Trait	How often it is seen
Sensorineural hearing impairment	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
Nasal speech	Often (30–79%)

Constitutional symptom

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

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 BAG3 and how often each is seen. Find out more at hpo.jax.org.

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