Traits

Traits linked to GP1BB

glycoprotein Ib platelet subunit beta

The Human Phenotype Ontology links 165 traits to GP1BB, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Impaired ristocetin-induced platelet aggregation	Always
Low platelet count	Always
Macrothrombocytopenia	Always
Neonatal alloimmune thrombocytopenia	Always
Bleeding tendency	Very often (80–99%)
Decreased platelet glycoprotein Ib-IX-V	Very often (80–99%)
Giant platelets	Very often (80–99%)
Large platelets	Very often (80–99%)
Abnormally heavy bleeding during menstruation	Often (30–79%)
Blood spots	Often (30–79%)
Cephalohematoma	Often (30–79%)
Gastrointestinal bleeding	Often (30–79%)
Petechiae	Often (30–79%)
Platelet anisocytosis	Often (30–79%)
Prolonged bleeding after dental extraction	Often (30–79%)
Recurring nosebleed	Often (30–79%)
Spontaneous hematomas	Often (30–79%)
Abnormal megakaryocyte morphology	Sometimes (5–29%)
Black feces	Sometimes (5–29%)
Bleeding gums	Sometimes (5–29%)
Bleeding within the skull	Sometimes (5–29%)
Bloody nose	Sometimes (5–29%)
Bruising susceptibility	Sometimes (5–29%)
Ecchymosis	Sometimes (5–29%)
Platelet abnormalities	Sometimes (5–29%)
Prolonged bleeding after surgery	Sometimes (5–29%)
Vomiting blood	Sometimes (5–29%)
Subarachnoid hemorrhage	Rarely (1–4%)
Prolonged bleeding time	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Abnormal facial shape	Very often (80–99%)
Bulbous nose	Very often (80–99%)
Cleft palate	Very often (80–99%)
Corners of eye widely separated	Very often (80–99%)
Eye folds	Very often (80–99%)
Flattening of the skull base	Very often (80–99%)
Prominent nasal bridge	Very often (80–99%)
Upward slanting of the opening between the eyelids	Very often (80–99%)
Wide nasal bridge	Very often (80–99%)
Abnormal dentition	Often (30–79%)
Abnormality of the eyelid	Often (30–79%)
Abnormality of the skull	Often (30–79%)
Dental cavities	Often (30–79%)
Long face	Often (30–79%)
Long philtrum	Often (30–79%)
Short neck	Often (30–79%)
Zygomatic flattening	Often (30–79%)
Abnormal tooth enamel	Sometimes (5–29%)
Abnormally small head	Sometimes (5–29%)
Blockage of the rear opening of the nasal cavity	Sometimes (5–29%)
Downward slanting of the opening between the eyelids	Sometimes (5–29%)
Little lower jaw	Sometimes (5–29%)
Multiple suture craniosynostosis	Sometimes (5–29%)
Narrow mouth	Sometimes (5–29%)
Retinal arteriolar tortuosity	Sometimes (5–29%)
Short philtrum	Sometimes (5–29%)
Tall shaped head	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Difficulty finding words	Very often (80–99%)
Anxiety	Often (30–79%)
Attention deficit	Often (30–79%)
Global developmental delay	Often (30–79%)
Intellectual disability, mild	Often (30–79%)
Meningocele	Often (30–79%)
Specific learning disability	Often (30–79%)
Arrhinencephaly	Sometimes (5–29%)
Autism	Sometimes (5–29%)
Behavioral abnormality	Sometimes (5–29%)
Bipolar disorder	Sometimes (5–29%)
Depression	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Intellectual disability	Sometimes (5–29%)
Parkinsonism	Sometimes (5–29%)
Schizophrenia	Sometimes (5–29%)
Split spine	Sometimes (5–29%)
Too much cerebrospinal fluid in the brain	Sometimes (5–29%)
Abnormality of the nervous system	Rarely (1–4%)
Cerebral palsy	Rarely (1–4%)
Migraine	Rarely (1–4%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Abnormal aortic arch morphology	Very often (80–99%)
Abnormal cardiovascular system morphology	Very often (80–99%)
Abnormal pulmonary valve morphology	Very often (80–99%)
An opening in the wall separating the top two chambers of the heart	Very often (80–99%)
Hole in heart wall separating two lower heart chambers	Very often (80–99%)
Small thymus	Very often (80–99%)
Tetralogy of Fallot	Very often (80–99%)
Truncus arteriosus	Very often (80–99%)
Abnormality of the tonsils	Often (30–79%)
Abnormal aortic valve morphology	Sometimes (5–29%)
Hypertensive crisis	Sometimes (5–29%)
Increased spleen size	Sometimes (5–29%)
Patent ductus arteriosus	Sometimes (5–29%)
Tricuspid atresia	Sometimes (5–29%)
Varicose veins	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Anorectal anomaly	Often (30–79%)
Constipation	Often (30–79%)
Absent anus	Sometimes (5–29%)
Acid reflux	Sometimes (5–29%)
Enlarged colon lacking nerve cells	Sometimes (5–29%)
Feeding difficulties in infancy	Sometimes (5–29%)
Gallstones	Sometimes (5–29%)
Inguinal hernia	Sometimes (5–29%)
Intestinal malrotation	Sometimes (5–29%)
Loss of bowel control	Sometimes (5–29%)
Umbilical hernia	Sometimes (5–29%)
Partially duplicated kidney	Rarely (1–4%)

Abnormality of the eye

Trait	How often it is seen
Drooping upper eyelid	Often (30–79%)
New blood vessel formation in cornea	Often (30–79%)
Posterior embryotoxon	Often (30–79%)
Abnormally small eyeball	Sometimes (5–29%)
Clouding of the lens of the eye	Sometimes (5–29%)
Cross-eyed	Sometimes (5–29%)
Glaucoma	Sometimes (5–29%)
Optic atrophy	Sometimes (5–29%)
Wide-set eyes	Sometimes (5–29%)
Blindness	Rarely (1–4%)

Abnormality of the genitourinary system

Trait	How often it is seen
Small kidneys	Often (30–79%)
Abnormal uterus bleeding	Sometimes (5–29%)
Abnormality of the uterus	Sometimes (5–29%)
Hypospadias	Sometimes (5–29%)
Multiple kidney cysts	Sometimes (5–29%)
Polycystic kidney dysplasia	Sometimes (5–29%)
Undescended testes	Sometimes (5–29%)
Vesicoureteral reflux	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Conductive deafness	Very often (80–99%)
Low-set ears	Very often (80–99%)
Chronic infections of the middle ear	Often (30–79%)
Hearing impairment	Often (30–79%)
Overfolded ears	Often (30–79%)
Small earlobe	Often (30–79%)
Bilateral sensorineural hearing impairment	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Very often (80–99%)
Intermittent involuntary muscle spasm	Often (30–79%)
Scoliosis	Often (30–79%)
Abnormality of the chest	Sometimes (5–29%)
Arthritis	Sometimes (5–29%)
Double-Jointed	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Long slender fingers	Often (30–79%)
Club feet	Sometimes (5–29%)
Dislocated kneecap	Sometimes (5–29%)
Duplication of bones of the toes	Sometimes (5–29%)
Extra finger	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Decreased immune function	Very often (80–99%)
Acne	Often (30–79%)
Seborrheic dermatitis	Often (30–79%)
Asthma	Sometimes (5–29%)
Autoimmunity	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Abnormality of the pharynx	Very often (80–99%)
Abnormal lung lobation	Sometimes (5–29%)
Chronic pulmonary obstruction	Sometimes (5–29%)
Partial or complete collapse of part or entire lung	Sometimes (5–29%)
Softening of voice box tissue	Sometimes (5–29%)

Growth abnormality

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

Abnormality of the endocrine system

Trait	How often it is seen
Decreased parathyroid hormone secretion	Often (30–79%)
Overactive thyroid	Sometimes (5–29%)
Underactive thyroid	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Low blood calcium levels	Often (30–79%)
Blood in urine	Sometimes (5–29%)
Bloody urine	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Impaired T cell function	Often (30–79%)

Abnormality of prenatal development or birth

Trait	How often it is seen
High levels of amniotic fluid	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Patchy loss of skin color	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
Nasal speech	Very often (80–99%)

Constitutional symptom

Trait	How often it is seen
Muscle ache	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 GP1BB and how often each is seen. Find out more at hpo.jax.org.

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