Traits

Traits linked to STAG1

STAG1 cohesin complex component

The Human Phenotype Ontology links 48 traits to STAG1, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of head or neck

Trait	How often it is seen
Prominent nasal bridge	Often (30–79%)
Thin eyebrow	Often (30–79%)
Wide mouth	Often (30–79%)
Abnormal facial shape	Sometimes (5–29%)
Abnormally small head	Sometimes (5–29%)
Central incisor gap	Sometimes (5–29%)
Cleft of the mouth	Sometimes (5–29%)
Gap between front teeth	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Increased nuchal translucency	Sometimes (5–29%)
Little lower jaw	Sometimes (5–29%)
Long eyelashes	Sometimes (5–29%)
Monobrow	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Intellectual disability	Always
Global developmental delay	Very often (80–99%)
Autism spectrum disorder	Often (30–79%)
Epilepsy	Often (30–79%)
Brain degeneration	Sometimes (5–29%)
Chiari type I malformation	Sometimes (5–29%)
Degeneration of cerebrum	Sometimes (5–29%)
Epileptic encephalopathy	Sometimes (5–29%)
Intellectual disability, severe	Sometimes (5–29%)
Delayed speech and language development	Not recorded

Abnormality of limbs

Trait	How often it is seen
Abnormality of the upper limb	Sometimes (5–29%)
Curvature of little finger	Sometimes (5–29%)
Limited elbow extension	Sometimes (5–29%)
Single transverse palmar crease	Sometimes (5–29%)
Webbed 2nd and 3rd toes	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Double-Jointed	Often (30–79%)
Low muscle tone	Sometimes (5–29%)
Low muscle tone, in neonatal onset	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Sometimes (5–29%)
Prenatal growth deficiency	Sometimes (5–29%)
Short stature	Sometimes (5–29%)
Small for gestational age	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Undescended testes	Often (30–79%)
Horseshoe kidney	Sometimes (5–29%)
Small male external genitalia	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Cutis marmorata	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Acid reflux	Often (30–79%)
Feeding difficulties	Often (30–79%)

Abnormality of the eye

Trait	How often it is seen
Deeply set eye	Very often (80–99%)
Cross-eyed	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Only one artery in umbilical cord instead of two	Sometimes (5–29%)

Abnormality of the breast

Trait	How often it is seen
Accessory nipple	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Low-set ears	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 STAG1 and how often each is seen. Find out more at hpo.jax.org.

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