Gene
C3
complement C3
- HGNC 1318(opens in a new tab)
- Ensembl gene ENSG00000125730(opens in a new tab)
- NCBI Gene 718(opens in a new tab)
Summary
- Cytogenetic location
- 19p13.3
- Coordinates
- Chromosome 19: 6,677,704–6,720,650 (GRCh38)
- Exons
- 41 exons across 42.9 kb
- Protein
- 1,663 amino acids
- Inheritance
- Autosomal dominant Autosomal recessive
- Also known as
- CPAMD1, ARMD9, C3a, C3b
- MANE Select transcript
- ENST00000245907.11NM_000064.4
- Locus type
- gene with protein product
- Very high
- Confident
- Low
- Very low
Reference genomeGRCh38hg38
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Inherited Complement and Properdin Deficiencies
- Complement component 3 deficiencyAutosomal recessive
Caused by changes in C3, it leads to severe recurrent bacterial infections and can cause kidney inflammation.
- 2 GenCC submitters rate it definitive or strong
What knowing changes
Vaccination against encapsulated bacteria and prompt treatment of infections reduce the risk of serious illness.
Hemolytic Uremic Syndrome, Interstitial Nephritis
- Atypical Hemolytic-Uremic Syndrome With C3 AnomalyAutosomal dominant
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
- Complement 3 Glomerulopathy
A kidney disease, including C3 glomerulonephritis and dense deposit disease, caused by uncontrolled activation of the complement system, often involving CFH, CFHR5, C3 or CFI.
- ClinGen rates the link moderate
What knowing changes
Knowing guides kidney monitoring and consideration of complement-targeted treatment.
- Atypical Hemolytic Uremic Syndrome With Complement Gene AbnormalityAutosomal dominant
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
- Atypical Hemolytic-Uremic SyndromeAutosomal dominant
A rare, genetic thrombotic microangiopathy due to dysregulation of the alternative complement pathway and characterized by the triad of hemolytic anemia, thrombocytopenia, and acute renal dysfunction.
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
- Hemolytic-Uremic Syndrome
Acute kidney injury associated with microangiopathic hemolytic anemia and thrombocytopenia.
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
- Hereditary Hemolytic Uremic Syndrome
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
Broader groupings
Other Inborn Errors of Immunity
- Inborn error of immunity
One of 114 genes linked to it
Inherited disorders of the immune system caused by changes in single genes, affecting how the body fights infection or regulates inflammation.
- ClinGen rates the link definitive
- 3 GenCC submitters rate it definitive or strong
- Immunodeficiency Disease
One of 170 genes linked to it
Disease in which there is a deficiency or defect in the mechanisms of immunity, either cellular or humoral.
- ClinGen rates the link definitive
- 3 GenCC submitters rate it definitive or strong
What knowing changes
HSCT for SCID and severe PIDs; immunoglobulin replacement (IVIG/SCIG) for antibody deficiencies; leniolisib (Joenja, FDA 2023) for APDS; gene therapy for ADA-SCID; abatacept for CTLA4/LRBA deficiency; prophylactic antibiotics; G-CSF for CGD
Inheritance
- Autosomal dominant
- One changed copy, from either parent, is enough. A parent who has one passes it on to each child with a one-in-two chance.
- Autosomal recessive
- It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.
How C3 is laid out
- Coding sequence
- Untranslated region
- Intron
- Direction of transcription
- Known disease-causing sites
- Stretches short reads find hard
Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.
Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).
Nearby genes from Ensembl release 116, on GRCh38.
Exons make up 5.2 kb of the gene's 42.9 kb; 4,992 of those bases code for the protein.
How a genome test reads C3
50
positions in C3 where ClinVar classes a change as pathogenic or likely pathogenic
None of them falls in a region short reads find hard.
A whole genome covers all 42.9 kb of C3, introns included, not only the 5.2 kb of exons.
Traits linked to C3
The Human Phenotype Ontology lists these as features of the rare conditions C3 can cause. Each trait's page lists the other genes linked to it.
External links
Gene records
Transcript
Protein
Where this comes from
- HGNC: the gene's symbol, name, other symbols and location.
- MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
- GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
- The ACMG secondary findings list, SF v3.2.
- ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
- The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
- Data release 2026.10.16-c6eea6bf.
Cite this page
Dante Labs. (n.d.). C3 gene: complement C3. Retrieved 16 October 2026, from https://dantelabs.com/genes/c3
Dante Labs. C3 gene: complement C3 [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/c3
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