Traits

Traits linked to ISCA1

iron-sulfur cluster assembly 1

The Human Phenotype Ontology links 23 traits to ISCA1, 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
Epilepsy	Always
Fewer and broader ridges in brain	Always
Global developmental delay	Always
Increased reflexes	Always
Leukodystrophy	Always
Ventriculomegaly	Always
Abnormal cerebral white matter morphology	Often (30–79%)
Elevated brain lactate level by MRS	Often (30–79%)
Loss of developmental milestones	Often (30–79%)
Inappropriate crying	Sometimes (5–29%)
Delayed myelination	Not recorded

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Often (30–79%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Pigmentary retinopathy	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Progressively abnormally small cranium	Sometimes (5–29%)
Abnormally small head	Rarely (1–4%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Feeding difficulties in infancy	Very often (80–99%)

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Often (30–79%)
Higher than normal levels of lactate in blood	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Hearing impairment	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Involuntary muscle stiffness, contraction, or spasm	Always

Growth abnormality

Trait	How often it is seen
Growth delay	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 ISCA1 and how often each is seen. Find out more at hpo.jax.org.

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