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hyper-IgM syndrome type 2 - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

hyper-IgM syndrome type 2

MONDO:0011528

Also known as:AICDA hyper-IgM syndromeActivation-induced cytidine deaminase deficiencyHIGM2

Overview

A hyper-IgM syndrome characterized by the absence of immunoglobulin class switch recombination, the lack of immunoglobulin somatic hypermutations, and lymph node hyperplasia caused by the presence of giant germinal centers.

GeneticsAutosomal recessive · AICDA (chr 12)

ResearchLimited published research (5 articles)

Clinical Presentation

Built from Human Phenotype Ontology (HPO) phenotype annotations and GeneReviews clinical descriptions. Features represent findings documented across known cases — not an exhaustive list of possible symptoms.

Features include always present findings: Recurrent infection of the gastrointestinal tract, Recurrent bacterial infections, Recurrent respiratory infections, and Decreased circulating IgA concentration and others; and very common findings: Increased circulating IgM level. 11 total HPO annotations.

Organ System	Phenotype Count	Example Features
Blood and immune system	5	Recurrent infection of the gastrointestinal tract, Recurrent upper and lower respiratory tract infections, Recurrent bacterial infections

Genetic Landscape

Assembled from HGNC gene records, ClinGen gene-disease validity evidence, and ClinVar pathogenic variant data. Validity classifications reflect the strength of published evidence linking each gene to this disease.

AICDA encodes activation induced cytidine deaminase (198 aa). Single-stranded DNA-specific cytidine deaminase. Highest expression in Cells EBV-transformed lymphocytes (86.0 TPM) and Small Intestine Terminal Ileum (0.9 TPM).

Hyper-IgM syndrome type 2 is caused by mutations in the AICDA gene on chromosome 12.

The AICDA protein participates in UNG (UNG2) and base excision repair remove uridine and 5-methylcytidine from chromatin containing histone H3.3 pathway.

AICDA is classified as a druggable target (Enzyme category) with score 0.0.

Diagnosis

Genetic testing for AICDA is available. Testing is considered confirmatory for diagnosis.

Prognosis

Phenotype severity distribution: 5 always present features, 1 very common feature, 1 common feature.

Research Landscape

Sourced from ClinicalTrials.gov and PubMed. Publication types are classified using NLM-curated article metadata; research type breakdowns reflect the nature of published work for this disease.

No clinical trials have been registered for hyper-IgM syndrome type 2.

5 publications have been identified in PubMed for hyper-IgM syndrome type 2. Research spans Case Report / Case Series (60%), Review / Meta-Analysis (20%), and Basic Science / Preclinical (20%).

Recent Publications

Dhaunsi G (2026). [PMID: 41984751](https://pubmed.ncbi.nlm.nih.gov/41984751/). *J Immunol Res*. [Basic Science / Preclinical]
Koveshnikova EA (2025). [PMID: 40649888](https://pubmed.ncbi.nlm.nih.gov/40649888/). *International journal of molecular sciences*. [Review / Meta-Analysis]
Agrebi N (2025). [PMID: 40529371](https://pubmed.ncbi.nlm.nih.gov/40529371/). *Frontiers in immunology*. [Case Report / Case Series]
Meshaal SS (2025). [PMID: 39513285](https://pubmed.ncbi.nlm.nih.gov/39513285/). *Annals of human genetics*. [Case Report / Case Series]
Nishikawa T (2025). [PMID: 40391217](https://pubmed.ncbi.nlm.nih.gov/40391217/). *Frontiers in immunology*. [Case Report / Case Series]

Data assembled from 7 of 12 sources · Last updated Sep 20, 2026, 2:11 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:605258

Orphanet

European rare disease database

Orphanet:101089

GARD

Genetic and Rare Diseases Info Center

GARD:10578

Questions for Your Care Team

→Should my partner and I meet with a genetic counselor to discuss carrier status and family planning?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

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hyper-IgM syndrome type 2

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

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