Traits

Traits linked to FBN2

fibrillin 2

The Human Phenotype Ontology links 64 traits to FBN2, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of limbs

Trait	How often it is seen
Congenital finger flexion contractures	Always
Elbow flexion contracture	Always
Inability to straighten knee	Always
Limited elbow extension	Very often (80–99%)
Limited knee straightening	Very often (80–99%)
Long slender fingers	Very often (80–99%)
Permanent flexion of the finger	Very often (80–99%)
Bowing of the long bones	Often (30–79%)
Inward turned thumb	Often (30–79%)
Knee contracture	Often (30–79%)
Partial knee cap dislocation	Often (30–79%)
Camptodactyly of toe	Sometimes (5–29%)
Club feet	Sometimes (5–29%)
Dislocated kneecap	Sometimes (5–29%)
Elbow dislocation	Sometimes (5–29%)
Hip contracture	Sometimes (5–29%)
Wrist flexion contracture	Sometimes (5–29%)
Finger bends toward pinky	Not recorded
Front half of foot turns inward	Not recorded
Underdeveloped calf muscles	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Arthrogryposis multiplex congenita	Very often (80–99%)
Congenital contracture	Very often (80–99%)
Congenital kyphoscoliosis	Very often (80–99%)
Flexed joint that cannot be straightened	Very often (80–99%)
Joint stiffness	Very often (80–99%)
Muscular abnormality	Very often (80–99%)
Scoliosis	Very often (80–99%)
Elbow contracture	Often (30–79%)
Kyphoscoliosis	Often (30–79%)
Permanent flexion of the finger or toe	Often (30–79%)
Funnel chest	Sometimes (5–29%)
Pigeon chest	Sometimes (5–29%)
Distal arthrogryposis	Not recorded
Osteopenia	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Bulge in wall of root of large artery that carries blood away from heart	Often (30–79%)
Mitral valve prolapse	Often (30–79%)
Abnormal cardiovascular system morphology	Sometimes (5–29%)
Bulge in wall of large artery that carries blood away from heart	Sometimes (5–29%)
An opening in the wall separating the top two chambers of the heart	Not recorded
Aortic valve has two leaflets rather than three	Not recorded
Hole in heart wall separating two lower heart chambers	Not recorded
Mitral regurgitation	Not recorded
Patent ductus arteriosus	Not recorded

Abnormality of head or neck

Trait	How often it is seen
High palate	Very often (80–99%)
Little lower jaw	Sometimes (5–29%)
Broad head shape	Not recorded
Frontal bossing	Not recorded
Long, narrow head	Not recorded
Scaphocephaly	Not recorded
Short neck	Not recorded

Abnormality of the eye

Trait	How often it is seen
Macular degeneration	Always
Choroidal neovascularization	Sometimes (5–29%)
Ectopia lentis	Sometimes (5–29%)
Close sighted	Not recorded
Decreased clarity of vision	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Abnormal connection between trachea and esophagus	Sometimes (5–29%)
Absence or narrowing of first part of small bowel	Sometimes (5–29%)
Intestinal malrotation	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Increased upper to lower segment ratio	Always
Slender build	Very often (80–99%)
Disproportionate tall stature	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Abnormally folded helix	Very often (80–99%)
Crumpled ear	Very often (80–99%)

Abnormality of the nervous system

Trait	How often it is seen
Motor 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 FBN2 and how often each is seen. Find out more at hpo.jax.org.

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