Traits

Traits linked to CYFIP2

cytoplasmic FMR1 interacting protein 2

The Human Phenotype Ontology links 57 traits to CYFIP2, 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 speech development	Always
Epilepsy	Always
Encephalopathy	Very often (80–99%)
Abnormality of coordination	Often (30–79%)
Decreased reflex response	Often (30–79%)
Delayed speech and language development	Often (30–79%)
EEG with burst suppression	Often (30–79%)
EEG with multifocal slow activity	Often (30–79%)
Global developmental delay	Often (30–79%)
Hypsarrhythmia	Often (30–79%)
Increased reflexes	Often (30–79%)
Intellectual disability	Often (30–79%)
Loss of developmental milestones	Often (30–79%)
Abnormal corpus callosum morphology	Sometimes (5–29%)
Abnormal gait	Sometimes (5–29%)
Abnormal myelination	Sometimes (5–29%)
Ataxia	Sometimes (5–29%)
Attention deficit	Sometimes (5–29%)
Autism	Sometimes (5–29%)
Behavioral abnormality	Sometimes (5–29%)
Brain degeneration	Sometimes (5–29%)
Degeneration of cerebrum	Sometimes (5–29%)
Diminished deep tendon reflex	Sometimes (5–29%)
Disorder of involuntary muscle movements	Sometimes (5–29%)
Impulsivity	Sometimes (5–29%)
Involuntary movements	Sometimes (5–29%)
Jerking	Sometimes (5–29%)
Mental deterioration	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Unsteady walk	Sometimes (5–29%)
Repeated seizures without recovery between them	Rarely (1–4%)
Degeneration of cerebellum	Not recorded
Epileptic encephalopathy	Not recorded
Ventriculomegaly	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Often (30–79%)
Highly arched eyebrow	Often (30–79%)
Asymmetry of the posterior head	Sometimes (5–29%)
Downward slanting of the opening between the eyelids	Sometimes (5–29%)
Failure of development of between one and six teeth	Sometimes (5–29%)
High forehead	Sometimes (5–29%)
Tented mouth	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Drooping upper eyelid	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Abnormal involuntary eye movements	Rarely (1–4%)
Abnormality of vision	Rarely (1–4%)
Optic atrophy	Rarely (1–4%)
Retina degeneration	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Generalized decreased muscle tone	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Sometimes (5–29%)
Poor head control	Sometimes (5–29%)
Rigidity	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Acid reflux	Sometimes (5–29%)
Feeding difficulties	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Often (30–79%)
Short stature	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Increased muscle tone of arm or leg	Rarely (1–4%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Less than 10 fetal movements in 12 hours	Sometimes (5–29%)

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 CYFIP2 and how often each is seen. Find out more at hpo.jax.org.

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