The C2 gene encodes a component of the complement system, part of the innate immune system involved in inflammation and immune response.
Gene SymbolC2
Full NameComplement Component 2
Chromosomal Location6p21.3 (MHC Class III)
Ensembl IDENSG00000166278
Associated DiseasesAge-Related Macular Degeneration, Systemic Lupus Erythematosus, Complement Deficiency
The C2 gene encodes complement component 2, a crucial protein in the classical complement pathway. C2 is a zymogen that, when cleaved by C1s, forms the C2a and C2b fragments.
The cleavage of C2 by activated C1s produces:
- C2a: Remains bound to C4b, forming the C4b2a complex (C3 convertase)
- C2b: Released as a fragment with potential vasoactive properties
The C4b2a complex (C3 convertase) then cleaves C3 into C3a and C3b, amplifying the complement cascade.
- Alzheimer's Disease: C2 is part of the complement system activated in AD brain. The C4b2a C3 convertase contributes to neuroinflammation.
- Age-Related Macular Degeneration: SNPs in the C2 gene region are associated with AMD risk, particularly in combination with CFH variants.
- Systemic Lupus Erythematosus: C2 deficiency is associated with increased SLE risk.
- The C2 deficiency is one of the most common complement deficiencies
- C2 null alleles are relatively common in Caucasian populations
- Liver: Primary site of complement protein synthesis
- Brain: Expressed by microglia and astrocytes
- Immune cells: Macrophages, monocytes
- Klein et al., Complement C2 variants in age-related macular degeneration (2005)
- Gold et al., Complement in Alzheimer's disease (2006)
- Janeway et al., Immunobiology (9th ed., 2016)
- Ricklin et al., Complement in disease (2013)
- Merle et al., Complement system (2015)