Traits

Traits linked to MFF

mitochondrial fission factor

The Human Phenotype Ontology links 34 traits to MFF, 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
Hypsarrhythmia	Always
Increased reflexes	Always
Loss of developmental milestones	Always
Motor delay	Always
Abnormal basal ganglia MRI signal intensity	Often (30–79%)
Abnormal thalamic MRI signal intensity	Often (30–79%)
Absent speech development	Often (30–79%)
Auditory sensitivity	Often (30–79%)
Decreased nerve conduction velocity	Often (30–79%)
Degeneration of cerebellum	Often (30–79%)
EEG abnormality	Often (30–79%)
Epilepsy	Often (30–79%)
Epileptic spasm	Often (30–79%)
Impaired use of nonverbal behaviors	Often (30–79%)
Profound global developmental delay	Often (30–79%)
Global developmental delay	Not recorded
Inability to walk	Not recorded
Peripheral neuropathy	Not recorded

Abnormality of the eye

Trait	How often it is seen
Abnormality of visual evoked potentials	Often (30–79%)
Optic atrophy	Often (30–79%)
Optic disc pallor	Often (30–79%)
Paralysis or weakness of muscles within or surrounding outer part of eye	Often (30–79%)
Visual impairment	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Involuntary muscle stiffness, contraction, or spasm	Always
Low muscle tone	Always
Muscle weakness	Always
Functional motor deficit	Often (30–79%)
Low muscle tone in trunk	Often (30–79%)

Abnormality of the digestive system

Trait	How often it is seen
Poor swallowing	Always
Feeding difficulties	Often (30–79%)
Nasogastric tube feeding	Often (30–79%)

Abnormal cellular phenotype

Trait	How often it is seen
Abnormal mitochondrial shape	Often (30–79%)

Abnormality of head or neck

Trait	How often it is seen
Development of small head that was not present at birth	Always

Growth abnormality

Trait	How often it is seen
Growth delay	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 MFF and how often each is seen. Find out more at hpo.jax.org.

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