Traits

Traits linked to CR2

complement C3d receptor 2

The Human Phenotype Ontology links 75 traits to CR2, by body system: features seen in people with one of the gene's rare conditions.

CR2

Abnormality of the immune system

Trait	How often it is seen
Combined immunodeficiency	Always
Decreased circulating isohemagglutinin concentration	Always
Decreased circulating specific pneumococcal antibody concentration	Always
Partial absence of specific antibody response to unconjugated pneumococcus polysaccharide	Always
Recurrent bronchitis	Always
Antinuclear antibody positivity	Very often (80–99%)
Anti-complement component C1q antibody positivity	Often (30–79%)
Anti-ribosome Po antibody positivity	Often (30–79%)
Anti-titin antibody positivity	Often (30–79%)
Antineutrophil antibody positivity	Often (30–79%)
Decreased circulating complement C3 concentration	Often (30–79%)
Decreased circulating complement C4 concentration	Often (30–79%)
Malar rash	Often (30–79%)
Anti-dsDNA antibody positivity	Sometimes (5–29%)
Anti-La/SS-B antibody positivity	Sometimes (5–29%)
Anti-nucleoporin 62 antibody positivity	Sometimes (5–29%)
Anti-phosphatidic acid antibody positivity	Sometimes (5–29%)
Anti-Ro52/TRIM21 antibody positivity	Sometimes (5–29%)
Anti-Sm antibody positivity	Sometimes (5–29%)
Anti-U1 ribonucleoprotein antibody positivity	Sometimes (5–29%)
Discoid lupus rash	Sometimes (5–29%)
Serositis	Sometimes (5–29%)
Autoimmunity	Not recorded
Meningitis	Not recorded
Recurrent bacterial infections	Not recorded
Recurrent infections	Not recorded
Recurrent pneumonia	Not recorded
Recurrent respiratory infections	Not recorded

Abnormal cellular phenotype

Trait	How often it is seen
Chronic absent circulating IgG4	Always
Chronic decreased circulating IgG1 concentration	Always
Decreased circulating IgA concentration	Always
Decreased circulating total IgG concentration	Always
Decreased circulating IgG concentration	Very often (80–99%)
Impaired T cell function	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Recurrent sinus disease	Always
Abnormal color of the oral mucosa	Sometimes (5–29%)
Abnormality of salivation	Sometimes (5–29%)
Inflammation of the lips	Sometimes (5–29%)
Mouth sore	Sometimes (5–29%)
Pink eye	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Increased spleen size	Always
High blood pressure	Often (30–79%)
Raynaud phenomenon	Often (30–79%)
Swollen lymph nodes	Sometimes (5–29%)
Follicular hyperplasia	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Decreased blood leukocyte number	Often (30–79%)
Hemolytic anemia	Sometimes (5–29%)
Low platelet count	Sometimes (5–29%)
Cancer of lymphatic system	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Chronic diarrhea	Always
Anorexia	Very often (80–99%)
Diarrhea	Not recorded
Enlarged liver	Not recorded

Laboratory abnormality

Trait	How often it is seen
Fever	Always
High urine protein levels	Very often (80–99%)
Blood in urine	Often (30–79%)
High urine neutrophil count	Often (30–79%)

Abnormality of the nervous system

Trait	How often it is seen
Depression	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Chorea	Rarely (1–4%)

Constitutional symptom

Trait	How often it is seen
Muscle ache	Always
Fatigue	Very often (80–99%)
Malaise	Very often (80–99%)

Abnormality of the genitourinary system

Trait	How often it is seen
Frequent urinary tract infections	Always
Lupus nephritis	Often (30–79%)

Abnormality of the integument

Trait	How often it is seen
Hair loss	Often (30–79%)
Photosensitive skin	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Arthritis	Often (30–79%)
Polyarticular arthritis	Often (30–79%)

Abnormality of the respiratory system

Trait	How often it is seen
Sore throat	Always
Permanent enlargement of the airways of the lungs	Not recorded

Abnormal tissue mass

Trait	How often it is seen
Abnormal tissue mass	Not recorded

Abnormality of the ear

Trait	How often it is seen
Recurrent middle ear infection	Always

Abnormality of the eye

Trait	How often it is seen
Noninflammatory retina disease	Rarely (1–4%)

Growth abnormality

Trait	How often it is seen
Weight loss	Very often (80–99%)

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 CR2 and how often each is seen. Find out more at hpo.jax.org.

One test. A lifetime of answers.

From $449Free shipping · Results in 6–8 weeks

Get my Genome Test