What is the official name of the C4A gene?
The official name of this gene is “complement component 4A (Rodgers blood group).”
C4A is the gene's official symbol. The C4A gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the C4A gene?
- From NCBI Gene:
This gene encodes the acidic 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 is cleaved to release C4 anaphylatoxin, an antimicrobial peptide and a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus and type I diabetes mellitus. 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. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2014]
- From UniProt:
Non-enzymatic component of 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.Derived from proteolytic degradation of complement C4, C4a anaphylatoxin is a mediator of local inflammatory process. It induces the contraction of smooth muscle, increases vascular permeability and causes histamine release from mast cells and basophilic leukocytes.
How are changes in the C4A gene related to health conditions?
- Genetics Home Reference provides information about systemic lupus erythematosus, which is associated with changes in the C4A gene.
- UniProt provides the following information about the C4A gene's known or predicted involvement in human disease.
Complement component 4A deficiency (C4AD): A rare defect of the complement classical pathway associated with the development of autoimmune disorders, mainly systemic lupus with or without associated glomerulonephritis. The disease is caused by mutations affecting the gene represented in this entry.
Systemic lupus erythematosus (SLE): 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. 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.
- NCBI Gene lists the following diseases or traits (phenotypes) known or believed to be associated with changes in the C4A gene.
- Blood group, Chido/Rodgers system
- Complement component 4a deficiency
- OMIM.org, a catalog designed for genetics professionals and researchers, provides the following information about the C4A gene and its association with health conditions.
Where is the C4A gene located?
Cytogenetic Location: 6p21.3
Molecular Location on chromosome 6: base pairs 31,982,056 to 32,002,679
The C4A gene is located on the short (p) arm of chromosome 6 at position 21.3.
More precisely, the C4A gene is located from base pair 31,982,056 to base pair 32,002,679 on chromosome 6.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about C4A?
You and your healthcare professional may find the following resources about C4A helpful.
- Genetic Testing Registry - Repository of genetic test information
You may also be interested in these resources, which are designed for genetics professionals and researchers.
- OMIM - Genetic disorder catalog
- Research Resources - Tools for researchers
What other names do people use for the C4A gene or gene products?
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding C4A?
The resources on this site should not be used as a substitute for
professional medical care or advice. Users seeking information about
a personal genetic disease, syndrome, or condition should consult with a qualified
See How can I find a genetics professional in my area? in the Handbook.