Traits

Traits linked to MB

myoglobin

The Human Phenotype Ontology links 11 traits to MB, 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
Axial muscle weakness	Very often (80–99%)
Centrally nucleated skeletal muscle fibers	Very often (80–99%)
Muscle degeneration	Very often (80–99%)
Decreased lung function due to weak breathing muscles	Often (30–79%)
Increased variability in muscle fiber diameter	Often (30–79%)
Type 1 muscle fiber predominance	Often (30–79%)

Abnormality of limbs

Trait	How often it is seen
Proximal lower limb muscle weakness	Always
Weakness of the intrinsic hand muscles	Very often (80–99%)

Abnormal cellular phenotype

Trait	How often it is seen
Sarcoplasmic bodies	Very often (80–99%)

Abnormality of the digestive system

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

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Always

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

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