C4B_2
protein-codingcomplement component 4B (Chido blood group), copy 2
Gene summary
This gene encodes the basic form of complement factor 4, part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. In addition, this gene exists as a long form and a short form due to the presence or absence of a 6.4 kb endogenous HERV-K retrovirus in intron 9. This GeneID and its associated RefSeq record represent a second copy of C4B found on ALT_REF_LOCI_7. [provided by RefSeq, Jul 2011]
MANE transcript
Inheritance
ClinVar variants
Top phenotype
Max pathogenic AF
External References & Databases
GenCC Phenotypes & Disease Associations
Curated gene-disease validity assertions and inheritance patterns
No GenCC data available for this gene.
ClinVar Associated Diseases & Phenotypes
Reported disease conditions connected to C4B_2 variants in ClinVar
No annotated ClinVar phenotypes.
ClinVar Variants & Pathogenicity by Type
Statistics based on transcript . Only rare variants are included.
We include only reliable ClinVar variants with their consequences to MANE Select, MANE Plus Clinical transcripts, or transcripts with TSL equal to 1. Click a count to filter the variants table below.
Slight differences between displayed counts and ClinVar may occur due to a different transcript/consequence chosen by our variant effect predictor, or because we classify Benign/Likely benign as Likely benign and Pathogenic/Likely pathogenic as Likely pathogenic.
| Effect | PathogenicP | Likely pathogenicLP | VUS | Likely benignLB | BenignB | Sum |
|---|---|---|---|---|---|---|
| synonymous | 0 | |||||
| missense | 0 | |||||
| nonsense | 0 | |||||
| start loss | 0 | |||||
| frameshift | 0 | |||||
| splice donor/acceptor (+/-2bp) | 0 | |||||
| Total | 0 | 0 | 0 | 0 | 0 | 0 |
Transcript Catalog
Annotated transcript isoforms across RefSeq and Ensembl databases
| Transcript ID | Source | Protein ID | Coding Exons | MANE Status |
|---|---|---|---|---|
| No transcripts match your selected source or search query. | ||||
Gene Ontology (GO) Annotations & Pathways
Biological processes, molecular functions, cellular components and pathways
Pathways ConsensusPathDB
- Innate Immune System
- Immune System
- Activation of C3 and C5
- Initial triggering of complement
- Regulation of Complement cascade
dbNSFP Gene Annotations
Source:
- Function
- FUNCTION: Non-enzymatic component of the C3 and C5 convertases and thus essential for the propagation of the classical complement pathway. Covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune aggregates and the clearance of IC through CR1 on erythrocytes. C4A isotype is responsible for effective binding to form amide bonds with immune aggregates or protein antigens, while C4B isotype catalyzes the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens.;
- Disease
- DISEASE: Systemic lupus erythematosus (SLE) [MIM:152700]: A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys and serosal membranes. It is of unknown etiology, but is thought to represent a failure of the regulatory mechanisms of the autoimmune system. The disease is marked by a wide range of system dysfunctions, an elevated erythrocyte sedimentation rate, and the formation of LE cells in the blood or bone marrow. {ECO:0000269|PubMed:10092831, ECO:0000269|PubMed:17503323}. Note=Disease susceptibility is associated with variations affecting the gene represented in this entry. Interindividual copy-number variation (CNV) of complement component C4 and associated polymorphisms result in different susceptibilities to SLE. The risk of SLE susceptibility has been shown to be significantly increased among subjects with only two copies of total C4. A high copy number is a protective factor against SLE.; DISEASE: Complement component 4B deficiency (C4BD) [MIM:614379]: A rare defect of the complement classical pathway associated with the development of autoimmune disorders, mainly systemic lupus with or without associated glomerulonephritis. {ECO:0000269|PubMed:3265961}. Note=The disease is caused by mutations affecting the gene represented in this entry.;