Traits

Traits linked to MPZ

myelin protein zero

The Human Phenotype Ontology links 85 traits to MPZ, 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 motor nerve conduction velocity	Always
Decreased number of peripheral myelinated nerve fibers	Always
Decreased reflex response	Always
Decreased sensation in extremities	Always
Decreased sensory nerve conduction velocity	Always
Delayed ability to stand	Always
Delayed ability to walk	Always
Impaired distal vibration sensation	Always
Motor delay	Always
Myelin tomacula	Always
Onion bulb formation	Always
Peripheral demyelination	Always
Persistent head lag	Always
Segmental peripheral demyelination/remyelination	Always
Sensory ataxia	Always
Wide based walk	Always
Abnormal gait	Often (30–79%)
Acute demyelinating polyneuropathy	Often (30–79%)
Clumsiness	Often (30–79%)
Decreased nerve conduction velocity	Often (30–79%)
Impaired pain sensation	Often (30–79%)
Impaired temperature sensation	Often (30–79%)
Impaired vibratory sensation	Often (30–79%)
Inability to coordinate movements when walking	Often (30–79%)
Limb ataxia	Often (30–79%)
Nerve damage causing decreased feeling and movement	Often (30–79%)
Peripheral axonal neuropathy	Often (30–79%)
Peripheral dysmyelination	Often (30–79%)
Postural tremor	Often (30–79%)
Somatic sensory dysfunction	Often (30–79%)
Unsteady walk	Often (30–79%)
Babinski sign	Sometimes (5–29%)
Action tremor	Not recorded
Axonal degeneration/regeneration	Not recorded
Decreased muscle movement	Not recorded
High stepping	Not recorded
Hypertrophic nerve changes	Not recorded
Inability to walk	Not recorded
Myelin outfoldings	Not recorded
Peripheral neuropathy	Not recorded
Upper limb postural tremor	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Distal muscle wasting	Always
Low muscle tone	Always
Muscle weakness	Always
Proximal neurogenic muscle weakness	Always
Scoliosis	Always
Weakness of outermost muscles	Always
Increased skeletal muscle cells	Often (30–79%)
Kyphoscoliosis	Often (30–79%)
Muscle degeneration	Often (30–79%)
Frequent falls	Sometimes (5–29%)
Cold-induced muscle cramps	Not recorded
Decreased lung function due to weak breathing muscles	Not recorded
Poor head control	Not recorded
Severely decreased muscle tone	Not recorded

Abnormality of limbs

Trait	How often it is seen
Distal lower limb muscle weakness	Always
Dropped arches	Always
High-arched foot	Always
Club feet	Often (30–79%)
Lower limb muscle weakness	Often (30–79%)
Intrinsic hand muscle atrophy	Sometimes (5–29%)
Knock knees	Sometimes (5–29%)
Decreased arm strength	Not recorded
Foot drop	Not recorded
Hammertoe	Not recorded
Limb muscle weakness	Not recorded
Split hand	Not recorded
Ulnar claw	Not recorded

Abnormality of the eye

Trait	How often it is seen
Abnormality of the pupil	Often (30–79%)
Involuntary, rapid, rhythmic eye movements	Often (30–79%)
Slow pupillary light response	Not recorded
Tonic pupil	Not recorded

Abnormality of the ear

Trait	How often it is seen
Hearing impairment	Often (30–79%)
Progressive sensorineural hearing impairment	Not recorded
Sensorineural hearing impairment	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Facial diplegia	Always
Tongue twitching	Always

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Often (30–79%)
Increased CSF protein concentration	Often (30–79%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Less than 10 fetal movements in 12 hours	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Poor swallowing	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Urinary bladder sphincter dysfunction	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Abnormality of the immune system	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Recurrent coughing spasms	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 MPZ and how often each is seen. Find out more at hpo.jax.org.

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