Traits

Traits linked to VMA21

vacuolar ATPase assembly factor VMA21

The Human Phenotype Ontology links 16 traits to VMA21, 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
Skeletal muscle autophagosome accumulation	Always
Flexed joint that cannot be straightened	Sometimes (5–29%)
Low muscle tone, in neonatal onset	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Difficulty running	Not recorded
Difficulty walking up stairs	Not recorded
Gowers sign	Not recorded
Muscle degeneration	Not recorded
Muscle tissue disease	Not recorded
Myotonia	Not recorded

Abnormality of limbs

Trait	How often it is seen
Proximal lower limb muscle weakness	Always
Wasting of thigh muscle	Always

Abnormality of the eye

Trait	How often it is seen
Limited extraocular movements	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Motor delay	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory function loss	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	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 VMA21 and how often each is seen. Find out more at hpo.jax.org.

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