AICDA
Chr 12ARactivation induced cytidine deaminase
Also known as: AID, ARP2, CDA2, HEL-S-284, HIGM2
This gene encodes a single-stranded DNA cytidine deaminase that is essential for somatic hypermutation, gene conversion, and class-switch recombination of immunoglobulin genes in germinal center B cells. Mutations cause autosomal recessive immunodeficiency with hyper-IgM type 2, characterized by defective antibody class switching and impaired humoral immune responses. The gene shows low constraint to loss-of-function variation (pLI near 0), consistent with its autosomal recessive inheritance pattern.
Primary Disease Associations & Inheritance
Definitive — sufficient evidence for diagnostic panels
2 total gene-disease associations curated
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Highly tolerant — LoF variants common in population
Mild missense constraint
This gene has evidence for multiple mechanisms of pathogenicity (gain-of-function and dominant-negative). Both the Badonyi & Marsh prediction and the broader genomic evidence point to gain-of-function as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.
Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.
Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.
ClinVar Variant Classifications
100 submitted variants in ClinVar
Classification Summary
Curated Variants Distribution
Classified variants from ClinVar · 5 ACMG categories
| Classification | LoF | Missense + Inframe | Non-coding | Synonymous | Total |
|---|---|---|---|---|---|
Pathogenic | 0 | 0 | 7 | 0 | 7 |
Likely Pathogenic | 2 | 2 | 1 | 0 | 5 |
VUS | 2 | 32 | 5 | 0 | 39 |
Likely Benign | 1 | 0 | 23 | 19 | 43 |
Benign | 0 | 0 | 6 | 0 | 6 |
| Total | 5 | 34 | 42 | 19 | 100 |
LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly
View in ClinVar →Protein Context — Lollipop Plot
AICDA · protein map & ClinVar variants
Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.
3D Protein StructureAlphaFold
External Resources
Links to major genomics databases and tools
Clinical Trials
Active and recruiting trials from ClinicalTrials.gov
No active trials found for this gene.
Search ClinicalTrials.gov →External Resources
Links to major genomics databases and tools