Traits

Traits linked to FDX2

ferredoxin 2

The Human Phenotype Ontology links 37 traits to FDX2, 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
Gowers sign	Always
Muscle spasm	Always
Proximal neurogenic muscle weakness	Always
Breakdown of skeletal muscle	Rarely (1–4%)
Involuntary muscle stiffness, contraction, or spasm	Rarely (1–4%)
Generalized decreased muscle tone	Not recorded
Low muscle tone	Not recorded
Mitochondrial myopathy	Not recorded
Muscle weakness	Not recorded

Laboratory abnormality

Trait	How often it is seen
3-Methylglutaconic aciduria	Always
Higher than normal levels of lactate in blood	Always
Highly elevated creatine kinase	Always
Increased lactate in body	Always
Ketonuria	Always
Myoglobinuria	Always
Elevated blood creatine phosphokinase	Rarely (1–4%)

Abnormality of the nervous system

Trait	How often it is seen
Waddling gait	Always
Increased reflexes	Rarely (1–4%)
Abnormal gait	Not recorded
Decreased reflex response	Not recorded
Motor delay	Not recorded
Nerve damage causing decreased feeling and movement	Not recorded

Abnormality of the eye

Trait	How often it is seen
Involuntary, rapid, rhythmic eye movements	Rarely (1–4%)
Optic atrophy	Rarely (1–4%)
Visual impairment	Rarely (1–4%)
Drooping upper eyelid	Not recorded

Abnormality of limbs

Trait	How often it is seen
Limb-girdle muscle weakness	Always
Lower limb muscle weakness	Always
High-arched foot	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Low blood neutrophil count	Rarely (1–4%)
Microcytic anemia	Rarely (1–4%)

Abnormal cellular phenotype

Trait	How often it is seen
Decreased activity of mitochondrial complex II	Always

Abnormality of head or neck

Trait	How often it is seen
Abnormally large tongue	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Enlarged liver	Not recorded

Abnormality of the endocrine system

Trait	How often it is seen
Underactive thyroid	Rarely (1–4%)

Abnormality of the respiratory system

Trait	How often it is seen
Breathing difficulty	Always

Constitutional symptom

Trait	How often it is seen
Muscle ache	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 FDX2 and how often each is seen. Find out more at hpo.jax.org.

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