Traits

Traits linked to SYT2

synaptotagmin 2

The Human Phenotype Ontology links 44 traits to SYT2, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the nervous system

Trait	How often it is seen
Absent reflexes	Always
Decreased compound muscle action potential amplitude	Very often (80–99%)
Compound muscle action potential amplitude facilitation	Often (30–79%)
Waddling gait	Often (30–79%)
Cerebellar vermis hypoplasia	Sometimes (5–29%)
Decreased sensation in extremities	Sometimes (5–29%)
Degeneration of cerebrum	Sometimes (5–29%)
Difficulty articulating speech	Sometimes (5–29%)
High pitched voice	Sometimes (5–29%)
Motor delay	Sometimes (5–29%)
Thin corpus callosum	Sometimes (5–29%)
Decreased reflex response	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Always
Distal muscle wasting	Often (30–79%)
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation	Often (30–79%)
Proximal neurogenic muscle weakness	Often (30–79%)
Scoliosis	Often (30–79%)
Tired easily	Often (30–79%)
Weakness of outermost muscles	Often (30–79%)
Decreased lung function due to weak breathing muscles	Sometimes (5–29%)
Increased variability in muscle fiber diameter	Sometimes (5–29%)
Wasting of muscles near the body	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Hammertoe	Very often (80–99%)
Foot drop	Often (30–79%)
High-arched foot	Often (30–79%)
Inability to straighten knee	Often (30–79%)
Ankle flexion contracture	Sometimes (5–29%)
Dropped arches	Sometimes (5–29%)
Elbow flexion contracture	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
Weak voice	Often (30–79%)
Nasal speech	Sometimes (5–29%)
Weak cry	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Weakness of facial musculature	Always
Tongue twitching	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Mitral stenosis	Sometimes (5–29%)
Narrowing of blood vessel below aortic heart valve	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Poor swallowing	Sometimes (5–29%)
Pyloric stenosis	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Limited extraocular movements	Often (30–79%)
Slow eye movements	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Less than 10 fetal movements in 12 hours	Often (30–79%)

Abnormality of the ear

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

Abnormality of the respiratory system

Trait	How often it is seen
Reduced forced vital capacity	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Faltering weight	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 SYT2 and how often each is seen. Find out more at hpo.jax.org.

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