Traits

Traits linked to SMC3

structural maintenance of chromosomes 3

The Human Phenotype Ontology links 142 traits to SMC3, by body system: features seen in people with one of the gene's rare conditions.

SMC3

Abnormality of head or neck

Trait	How often it is seen
Curly eyelashes	Always
Decreased volume of lip	Always
Widely spaced teeth	Always
Abnormally small head	Very often (80–99%)
Broad head shape	Very often (80–99%)
Bulbous nose	Very often (80–99%)
Delayed eruption of teeth	Very often (80–99%)
Depressed nasal bridge	Very often (80–99%)
Downturned corners of mouth	Very often (80–99%)
High palate	Very often (80–99%)
Highly arched eyebrow	Very often (80–99%)
Little lower jaw	Very often (80–99%)
Long eyelashes	Very often (80–99%)
Long philtrum	Very often (80–99%)
Low frontal hairline	Very often (80–99%)
Low hairline at back of neck	Very often (80–99%)
Monobrow	Very often (80–99%)
Nasal tip, upturned	Very often (80–99%)
Short neck	Very often (80–99%)
Short nose	Very often (80–99%)
Thick eyebrow	Very often (80–99%)
Thin red part of the upper lip	Very often (80–99%)
Baggy eyes	Often (30–79%)
Blocked tear duct	Often (30–79%)
Broad nasal tip	Often (30–79%)
Development of small head that was not present at birth	Often (30–79%)
Eye folds	Often (30–79%)
Inflammation of eyelids	Often (30–79%)
Narrow forehead	Often (30–79%)
Receding chin	Often (30–79%)
Short chin	Often (30–79%)
Small head present at birth	Often (30–79%)
Smooth philtrum	Often (30–79%)
Asymmetry of the posterior head	Sometimes (5–29%)
Blockage of the rear opening of the nasal cavity	Sometimes (5–29%)
Cleft palate	Sometimes (5–29%)
Decreased size of tooth	Sometimes (5–29%)
Delayed closure of the soft spot on the skull	Sometimes (5–29%)
Facial asymmetry	Sometimes (5–29%)
Flat face	Sometimes (5–29%)
Frontal bossing	Sometimes (5–29%)
Hooded eyelid	Sometimes (5–29%)
Increased nuchal translucency	Sometimes (5–29%)
Laterally extended eyebrow	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Attachment of thumb close to wrist	Always
Shortened 4th long bone of hand	Always
Webbed 2nd and 3rd toes	Always
Fused toes	Very often (80–99%)
Short foot	Very often (80–99%)
Shortened 1st long bone of hand	Very often (80–99%)
Small hand	Very often (80–99%)
Smaller or shorter than typical limbs	Very often (80–99%)
Bilateral single transverse palmar creases	Often (30–79%)
Curvature of little finger	Often (30–79%)
Elbow dislocation	Often (30–79%)
Fused forearm bones	Often (30–79%)
Limited elbow movement	Often (30–79%)
Short 5th finger	Often (30–79%)
Shortened 5th long bone of hand	Often (30–79%)
Single transverse palmar crease	Often (30–79%)
Abnormal morphology of ulna	Sometimes (5–29%)
Hip dislocation	Sometimes (5–29%)
Oligodactyly	Sometimes (5–29%)
Talipes	Sometimes (5–29%)
Short fingers or toes	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Global developmental delay	Always
Intellectual disability	Always
Abnormally low-pitched voice	Very often (80–99%)
Intellectual disability, severe	Very often (80–99%)
Abnormal speech pattern	Often (30–79%)
Anxiety	Often (30–79%)
Attention deficit	Often (30–79%)
Delayed motor skills	Often (30–79%)
Difficulty sleeping	Often (30–79%)
Obsessive compulsive behavior	Often (30–79%)
Absent/small cerebellum	Sometimes (5–29%)
Autism	Sometimes (5–29%)
Decrease in size of the outer layer of the brain due to loss of brain cells	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Peripheral neuropathy	Sometimes (5–29%)
Ventriculomegaly	Sometimes (5–29%)
Cognitive impairment	Not recorded
Poor speech	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Hypospadias	Often (30–79%)
Multicystic kidney dysplasia	Often (30–79%)
Small labia majora	Often (30–79%)
Underdeveloped penis	Often (30–79%)
Undescended testes	Often (30–79%)
Vesicoureteral reflux	Often (30–79%)
Abnormality of the uterus	Sometimes (5–29%)
Hydroureter	Sometimes (5–29%)
Primary amenorrhea	Sometimes (5–29%)
Renal failure	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Patent foramen ovale	Always
Cutis marmorata	Often (30–79%)
Abnormal cardiovascular system morphology	Sometimes (5–29%)
An opening in the wall separating the top two chambers of the heart	Sometimes (5–29%)
Aortic valve has two leaflets rather than three	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Narrowing of pulmonic valve	Sometimes (5–29%)
Patent ductus arteriosus	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Close sighted	Often (30–79%)
Cornea of eye less than 10mm in diameter	Often (30–79%)
Drooping upper eyelid	Often (30–79%)
Phthisis bulbi	Often (30–79%)
Clouding of the lens of the eye	Sometimes (5–29%)
Cross-eyed	Sometimes (5–29%)
Glaucoma	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Absent ear canal	Very often (80–99%)
Conductive deafness	Often (30–79%)
Ears rotated toward back of head	Often (30–79%)
Hearing impairment	Often (30–79%)
Low-set ears	Often (30–79%)
Sensorineural hearing impairment	Often (30–79%)
Large ears	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Delayed bone maturation	Very often (80–99%)
Spasticity and rigidity of muscles	Very often (80–99%)
Joint stiffness	Often (30–79%)
Abnormal formation of the hip	Sometimes (5–29%)
Congenital diaphragmatic hernia	Sometimes (5–29%)
Funnel chest	Sometimes (5–29%)
Low muscle tone	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Acid reflux	Very often (80–99%)
Feeding difficulties in infancy	Often (30–79%)
Intestinal malrotation	Sometimes (5–29%)
Pyloric stenosis	Sometimes (5–29%)
Volvulus	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Short stature	Always
Faltering weight	Often (30–79%)
Prenatal growth deficiency	Often (30–79%)
Severe growth delay in children	Often (30–79%)
Truncal obesity	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Excessive hairiness	Very often (80–99%)
Excessive hairiness over body	Very often (80–99%)
port-wine stain	Sometimes (5–29%)
Thick hair	Not recorded

Abnormality of prenatal development or birth

Trait	How often it is seen
Premature birth	Often (30–79%)
Prenatal movement abnormality	Sometimes (5–29%)

Abnormality of the breast

Trait	How often it is seen
Small nipples	Often (30–79%)

Abnormality of the endocrine system

Trait	How often it is seen
Delayed puberty	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 SMC3 and how often each is seen. Find out more at hpo.jax.org.

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