AICDA: Activation-Induced Cytidine Deaminase
Key enzyme in antibody diversification and hyper-IgM syndrome type 2
Gene Information Card
| Symbol | AICDA |
|---|---|
| Full Name | activation-induced cytidine deaminase |
| Gene Type | protein-coding |
| Chromosomal Location | 12p13.31 |
| NCBI Gene ID | 57379 ncbi.nlm.nih.gov/gene/57379 |
| Ensembl ID | ENSG00000111732 |
| UniProt ID | Q9GZX7 |
| OMIM ID | 605257 |
| HGNC ID | 13203 |
| Aliases | AID, ARP2, CDA2, HIGM2 |
Description
The AICDA gene encodes activation-induced cytidine deaminase (AID), a DNA-editing enzyme expressed primarily in activated B cells. AID initiates somatic hypermutation (SHM) and class switch recombination (CSR) by deaminating cytosine to uracil in immunoglobulin genes, enabling antibody affinity maturation and isotype switching. Mutations in AICDA cause autosomal recessive hyper-IgM syndrome type 2 (HIGM2), characterized by defective CSR and SHM, recurrent infections, and elevated IgM levels.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Hyper-IgM syndrome type 2 (HIGM2) | Loss-of-function mutations in AICDA impair class switch recombination and somatic hypermutation, leading to defective antibody diversification. | OMIM #605257; ClinVar; PMID: 10700184 |
| Lymphoma (diffuse large B-cell lymphoma) | Aberrant AID expression can cause off-target DNA damage and translocations in non-immunoglobulin genes, contributing to lymphomagenesis. | COSMIC; PMID: 17981137 |
| Autoimmune diseases (e.g., systemic lupus erythematosus) | Dysregulated AID activity may promote autoantibody production through ectopic somatic hypermutation. | PMID: 17660828 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lymph node | 0.6 | Low |
| Spleen | 0.4 | Low |
| Bone marrow | 0.2 | Low |
| Tonsil | 0.8 | Low |
| Appendix | 0.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Raji (Burkitt lymphoma) | 1.2 | B-cell line, high AICDA expression |
| Daudi (Burkitt lymphoma) | 0.9 | B-cell line, moderate expression |
| RPMI-8226 (myeloma) | 0.1 | Plasma cell line, low expression |
| HEK293 (embryonic kidney) | 0.0 | Non-B cell, no expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.70C>T (p.Arg24Ter) | Nonsense | Reported in HIGM2 | Loss of function; premature stop codon |
| c.272T>C (p.Leu91Pro) | Missense | Reported in HIGM2 | Loss of function; impaired catalytic activity |
| c.334C>T (p.Arg112Cys) | Missense | Reported in HIGM2 | Loss of function; reduced deaminase activity |
| c.398G>A (p.Arg133Gln) | Missense | Reported in HIGM2 | Loss of function; defective nuclear localization |
Mutation functional classification
Loss of Function (LOF)
Most AICDA mutations in HIGM2 are loss-of-function, impairing deaminase activity, nuclear localization, or protein stability, leading to defective CSR and SHM.
Gain of Function (GOF)
Not well documented; aberrant overexpression in B-cell lymphomas may act as a gain-of-function by increasing off-target mutagenesis.
Dominant Negative (DN)
Not reported for AICDA; all known pathogenic mutations are recessive.
View complete mutation data：
Gene Ontology (GO)
| • GO:0008270 - zinc ion binding | • GO:0009982 - cytidine deaminase activity |
| • GO:0005654 - nucleoplasm | • GO:0005737 - cytoplasm |
| • GO:0006304 - DNA modification | • GO:0006310 - DNA recombination |
| • GO:0016446 - somatic hypermutation of immunoglobulin genes | • GO:0045190 - isotype switching |
Pathways
• Class switch recombination (CSR)
• Somatic hypermutation (SHM)
• DNA damage response (via UNG and MSH2/MSH6)
Protein Summary
Activation-induced cytidine deaminase (AID) is a 198-amino acid protein containing a cytidine deaminase domain and a nuclear localization signal. It catalyzes the deamination of cytosine to uracil in single-stranded DNA, primarily at immunoglobulin loci. This initiates error-prone DNA repair pathways (base excision repair and mismatch repair) that introduce mutations (SHM) or DNA double-strand breaks leading to CSR. AID activity is tightly regulated by subcellular localization, phosphorylation, and interaction with cofactors. Dysregulation contributes to B-cell malignancies and autoimmunity.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| AICDA Knockout HEK293 Cell Line | EDJ-KQ2587 | Human | 57379 | Details Get a Quote |
| AICDA Knockout HeLa Cell Line | EDJ-KQ56831 | Human | 57379 | Details Get a Quote |
| AICDA Knockout A-549 Cell Line | EDJ-KQ65341 | Human | 57379 | Details Get a Quote |
| AICDA Knockout HCT 116 Cell Line | EDJ-KQ73780 | Human | 57379 | Details Get a Quote |
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