Traits

Traits linked to FBN1

fibrillin 1

The Human Phenotype Ontology links 303 traits to FBN1, 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
Big calvaria	Always
Broad forehead	Always
Deficient area between the eyebrows	Always
Downward slanting of the opening between the eyelids	Always
Dry eye syndrome	Always
High palate	Always
High, narrow palate	Always
Narrow nasal ridge	Always
Narrow nose	Always
Prominent forehead	Always
Prominent nasal bridge	Always
Receding chin	Always
Triangular face	Always
Abnormality of the eyebrow	Very often (80–99%)
Corners of eye widely separated	Very often (80–99%)
Little lower jaw	Very often (80–99%)
Long eyelashes	Very often (80–99%)
Long philtrum	Very often (80–99%)
Long, narrow head	Very often (80–99%)
Nasal tip, upturned	Very often (80–99%)
Round face	Very often (80–99%)
Short nose	Very often (80–99%)
Big lower jaw	Often (30–79%)
Bulbous nose	Often (30–79%)
Decreased size of maxilla	Often (30–79%)
Deformity of the skull	Often (30–79%)
Frontal bossing	Often (30–79%)
Full lower lip	Often (30–79%)
High forehead	Often (30–79%)
Increased size of nasopharyngeal adenoids	Often (30–79%)
Narrow mouth	Often (30–79%)
Thin red part of the upper lip	Often (30–79%)
Wide nasal bridge	Often (30–79%)
Zygomatic flattening	Often (30–79%)
Abnormally small head	Sometimes (5–29%)
Dental crowding	Sometimes (5–29%)
Midface retrusion	Sometimes (5–29%)
Abnormal dental position	Not recorded
Abnormality of dental shape	Not recorded
Broad head shape	Not recorded
Broad skull	Not recorded
Decreased depth of eye sockets	Not recorded
Deep philtrum	Not recorded
Depressed nasal bridge	Not recorded
Full cheeks	Not recorded
Long face	Not recorded
Narrow face	Not recorded
Narrow palate	Not recorded
Scaphocephaly	Not recorded
Smooth philtrum	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Ascending aortic dissection	Always
Bulge in wall of large artery that carries blood away from heart	Always
Bulge in wall of root of large artery that carries blood away from heart	Always
Cardiac failure	Always
Mitral regurgitation	Always
Mitral valve prolapse	Always
Tricuspid regurgitation	Always
Abnormal cardiac ventricle morphology	Very often (80–99%)
Abnormality of the cardiovascular system	Very often (80–99%)
Bulging of wall of large artery located above heart	Very often (80–99%)
Cutis marmorata	Very often (80–99%)
Heart murmur	Very often (80–99%)
Mucoid extracellular matrix accumulation	Very often (80–99%)
Tricuspid valve prolapse	Very often (80–99%)
Abnormal aortic valve morphology	Often (30–79%)
Abnormal cardiovascular system morphology	Often (30–79%)
Abnormal left ventricular function	Often (30–79%)
Aortic regurgitation	Often (30–79%)
Descending aortic dissection	Often (30–79%)
Enlarged heart	Often (30–79%)
High blood pressure	Often (30–79%)
increased pulmonary artery pressure	Often (30–79%)
Plaque build-up in arteries supplying blood to heart	Often (30–79%)
Valvular pulmonary stenosis	Often (30–79%)
Abdominal aortic aneurysm	Sometimes (5–29%)
Aortic valve has two leaflets rather than three	Sometimes (5–29%)
Brain aneurysm	Sometimes (5–29%)
Carotid artery dilatation	Sometimes (5–29%)
Depleted blood volume	Sometimes (5–29%)
Descending thoracic aorta aneurysm	Sometimes (5–29%)
Hole in center of heart	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Increased blood pressure in blood vessels of lungs	Sometimes (5–29%)
Ischemic stroke	Sometimes (5–29%)
Mini stroke	Sometimes (5–29%)
Mitral stenosis	Sometimes (5–29%)
Narrowing of aortic valve	Sometimes (5–29%)
Narrowing of pulmonic valve	Sometimes (5–29%)
Patent ductus arteriosus	Sometimes (5–29%)
Peripheral arterial stenosis	Sometimes (5–29%)
Prolonged QTc interval	Sometimes (5–29%)
Stroke	Sometimes (5–29%)
Tear in inner wall of large artery that carries blood away from heart	Sometimes (5–29%)
Tricuspid stenosis	Sometimes (5–29%)
Mitral annular calcification	Not recorded
Pulmonary artery dilatation	Not recorded

Abnormality of limbs

Trait	How often it is seen
Elbow flexion contracture	Always
Finger joint hyperextensibility	Always
Flexion contracture of toe	Always
Long fingers	Always
Long slender fingers	Always
Pes valgus	Always
Short finger	Always
Short foot	Always
Short long bone of foot	Always
Short palm	Always
Shortened long bone of hand	Always
Winged shoulder blade	Always
Dropped arches	Very often (80–99%)
Inability to straighten knee	Very often (80–99%)
Inward turned thumb	Very often (80–99%)
Long toe	Very often (80–99%)
Short fingers or toes	Very often (80–99%)
Short thumb	Very often (80–99%)
Small hand	Very often (80–99%)
Talipes calcaneovarus	Very often (80–99%)
Abnormally indented hip sockets	Often (30–79%)
High-arched foot	Often (30–79%)
Increased arm span	Often (30–79%)
Narrow foot	Often (30–79%)
Permanent flexion of the finger	Often (30–79%)
Abnormality of the thighbone	Sometimes (5–29%)
Abnormality of the wide portion of a long bone	Sometimes (5–29%)
Bowing of the long bones	Sometimes (5–29%)
Elbow dislocation	Sometimes (5–29%)
Equinus calcaneus	Sometimes (5–29%)
Fifth metacarpal with ulnar notch	Sometimes (5–29%)
Front half of foot turns inward	Sometimes (5–29%)
Knock knees	Sometimes (5–29%)
Limited elbow extension	Sometimes (5–29%)
Talipes	Sometimes (5–29%)
Back knee	Not recorded
Broad palm	Not recorded
Hammertoe	Not recorded
Medial rotation of the medial malleolus	Not recorded
Short finger bones	Not recorded
Wide hand bones	Not recorded
Wide long bone of foot	Not recorded
Wide long bones of hand	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Absent fat below the skin	Always
Delayed bone maturation	Always
Generalized lipodystrophy	Always
Hunched back	Always
Limitation of joint mobility	Always
Loss of fat tissue in localized area	Always
Low muscle tone	Always
Narrow chest	Always
Permanent flexion of the finger or toe	Always
Abnormality of connective tissue	Very often (80–99%)
Flexed joint that cannot be straightened	Very often (80–99%)
Joint stiffness	Very often (80–99%)
Limited shoulder movement	Very often (80–99%)
Pigeon chest	Very often (80–99%)
Wide rib cage	Very often (80–99%)
Double-Jointed	Often (30–79%)
Funnel chest	Often (30–79%)
Joint contracture	Often (30–79%)
Phalangeal cone-shaped epiphyses	Often (30–79%)
Scoliosis	Often (30–79%)
Short long bone	Often (30–79%)
Thoracic lordosis	Often (30–79%)
Abnormal formation of the hip	Sometimes (5–29%)
Abnormal shape of end part of bone	Sometimes (5–29%)
Abnormal vertebral body morphology	Sometimes (5–29%)
Abnormality of the sternum	Sometimes (5–29%)
Inability to make and keep healthy fat tissue	Sometimes (5–29%)
Kyphoscoliosis	Sometimes (5–29%)
Missing ribs	Sometimes (5–29%)
Muscle weakness	Sometimes (5–29%)
Muscular abnormality	Sometimes (5–29%)
Osteopenia	Sometimes (5–29%)
Ovoid vertebral bodies	Sometimes (5–29%)
Broad ribs	Not recorded
Cone-shaped end part of bone	Not recorded
Decreased muscle mass	Not recorded
Displacement of one backbone compared to another	Not recorded
Excessive inward curvature of lower spine	Not recorded
Narrow spinal canal	Not recorded
Premature osteoarthritis	Not recorded
Thin bony cortex	Not recorded

Abnormality of the eye

Trait	How often it is seen
Astigmatism	Always
Bulging eye	Always
Completely dislocated lens	Always
Decreased clarity of vision	Always
Deeply set eye	Always
Ectopia lentis	Always
Iridodonesis	Always
Microspherophakia	Always
Severe near sightedness	Always
Shallow anterior chamber	Always
Enlarged cornea	Very often (80–99%)
Glaucoma	Very often (80–99%)
Wide-set eyes	Very often (80–99%)
Abnormality of the iris	Often (30–79%)
Blue outer white part of eyeball	Often (30–79%)
Close sighted	Often (30–79%)
Clouding of the lens of the eye	Often (30–79%)
Cross-eyed	Often (30–79%)
Drooping upper eyelid	Often (30–79%)
Displaced pupil	Sometimes (5–29%)
Farsightedness	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Lazy eye	Sometimes (5–29%)
Outward facing eye ball	Sometimes (5–29%)
Retinal detachment	Sometimes (5–29%)
Visual impairment	Sometimes (5–29%)
Visual loss	Sometimes (5–29%)
Hypertropia	Rarely (1–4%)
Inferior oblique muscle overaction	Rarely (1–4%)
Inward turning cross eyed	Rarely (1–4%)
Blindness	Not recorded
Increased front to back length of eyeball	Not recorded
Underdeveloped iris	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Dural ectasia	Always
Lateral ventricular asymmetry	Always
Motor delay	Always
Too much cerebrospinal fluid in the brain	Always
Intellectual disability	Very often (80–99%)
Cognitive impairment	Often (30–79%)
Communicating hydrocephalus	Often (30–79%)
Decreased nerve conduction velocity	Often (30–79%)
Decreased reflex response	Often (30–79%)
Chiari malformation	Sometimes (5–29%)
Constrictive median neuropathy	Sometimes (5–29%)
Impaired pain sensation	Sometimes (5–29%)
Intellectual disability, mild	Sometimes (5–29%)
Obstructive sleep apnea	Sometimes (5–29%)
Peripheral neuropathy	Sometimes (5–29%)
Toe walking	Sometimes (5–29%)
Ventriculomegaly	Sometimes (5–29%)
Spontaneous cerebrospinal fluid leak	Rarely (1–4%)

Abnormality of the respiratory system

Trait	How often it is seen
Emphysema	Always
Low blood oxygen level	Very often (80–99%)
Neonatal respiratory distress	Very often (80–99%)
Exertional breathlessness	Often (30–79%)
Obstructive lung disease	Often (30–79%)
Paroxysmal dyspnea	Often (30–79%)
Abnormality in area between air sacs in lung	Sometimes (5–29%)
Apnea	Sometimes (5–29%)
Collapsed lung	Sometimes (5–29%)
Coughing up blood	Sometimes (5–29%)
Floppy windpipe	Sometimes (5–29%)
Laryngeal stenosis	Sometimes (5–29%)
Narrowing of windpipe	Sometimes (5–29%)
Respiratory function loss	Sometimes (5–29%)
Softening of voice box tissue	Sometimes (5–29%)
Stiff lung or chest wall causing decreased lung volume	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Beauty mark	Always
Premature aged appearance	Always
Stiff skin	Always
Stretch marks	Always
Tight skin	Always
Hanging skin	Very often (80–99%)
Thickened skin	Very often (80–99%)
Excessive hair growth	Often (30–79%)
Patchy darkened skin	Often (30–79%)
Absent/small skin	Sometimes (5–29%)
Firm lump under the skin	Sometimes (5–29%)
Hyperelastic skin	Sometimes (5–29%)
Reduced fat tissue below the skin	Not recorded

Growth abnormality

Trait	How often it is seen
Disproportionate tall stature	Always
Prenatal growth deficiency	Always
Short stature	Always
Tall stature	Always
Severe short stature	Very often (80–99%)
Small for gestational age	Very often (80–99%)
Reduced upper to lower segment ratio	Often (30–79%)
Decreased body weight	Sometimes (5–29%)
Faltering weight	Sometimes (5–29%)
Proportionate short stature	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Belly sticks out	Always
Feeding difficulties in infancy	Always
Umbilical hernia	Always
Feeding difficulties	Very often (80–99%)
Acid reflux	Often (30–79%)
Inguinal hernia	Often (30–79%)
Absent/small abdominal wall muscles	Sometimes (5–29%)
Enlarged liver	Sometimes (5–29%)
Incisional hernia	Not recorded

Abnormality of the ear

Trait	How often it is seen
Thickened helices	Always
Ears rotated toward back of head	Very often (80–99%)
Low-set ears	Very often (80–99%)
Conductive deafness	Often (30–79%)
Crumpled ear	Often (30–79%)
Prominent ear	Sometimes (5–29%)
Sensorineural hearing impairment	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Premature birth	Always
High levels of amniotic fluid	Often (30–79%)
Short fetal thigh bone length	Often (30–79%)
Low levels of amniotic fluid	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Decreased testicular size	Very often (80–99%)
Kidney stone	Sometimes (5–29%)
Undescended testes	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Asthma	Often (30–79%)
Recurrent ear infections	Often (30–79%)
Autoimmune antibody positivity	Rarely (1–4%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Bruising susceptibility	Sometimes (5–29%)
Subarachnoid hemorrhage	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Abnormal circulating lipid concentration	Sometimes (5–29%)
Noninsulin-dependent diabetes	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Underactive thyroid	Rarely (1–4%)

Abnormality of the voice

Trait	How often it is seen
Hoarse voice	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Chest pain	Often (30–79%)

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 FBN1 and how often each is seen. Find out more at hpo.jax.org.

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