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MHC class II deficiency

MHC Class II Deficiency Deep Research Fallback

⚠️ Fallback MONDO:0008855

MHC Class II Deficiency Deep Research Fallback

Provider Attempts

  • falcon: just research-disorder falcon MHC_Class_II_Deficiency started and remained silent for more than three minutes; terminated with signal 15.
  • openai: just research-disorder openai MHC_Class_II_Deficiency started and remained silent for more than three minutes; terminated with signal 15.
  • openscientist: just research-disorder openscientist MHC_Class_II_Deficiency started and remained silent for more than two minutes; terminated with signal 15.

Because the providers did not return a usable report, curation proceeded from generated Orphanet ORPHA:572 and fetched PubMed references. The YAML integrates the literature-backed synthesis below.

Integrated Literature Synthesis

MHC class II deficiency is a regulatory-gene disorder rather than a primary defect in the HLA class II structural loci. Reviews and original complementation studies identify CIITA, RFXANK, RFX5, and RFXAP as the central genes controlling MHC-II expression. CIITA acts as the class II transactivator, while RFXANK, RFX5, and RFXAP form the RFX complex that binds the conserved X-box in MHC-II promoters. Patient-cell studies show that wild-type CIITA or RFXAP can restore MHC class II expression in mutant cells.

The core pathophysiology is failure of MHC-II transcription and surface expression. Loss of MHC-II antigen presentation impairs CD4-positive T-helper cell development and T-helper-cell-dependent antibody production, producing combined cellular and humoral immunodeficiency. Human series support early infantile onset with recurrent bronchopulmonary infections, chronic diarrhea, failure to thrive, absent HLA-DR expression on B cells and monocytes, reduced CD4 T-cell counts, and reduced immunoglobulin levels. Orphanet frequency rows were used for the phenotype frequencies.

Thymic epithelial effects are supported by mouse and patient-based work showing perturbed thymic structure/function, impaired lymphostromal cross-talk, altered mTEC maturation, central tolerance defects, and peripheral tolerance perturbation. This supports a tolerance/autoimmunity node separate from the infection-oriented combined immunodeficiency node.

Treatment evidence supports hematopoietic cell transplantation as the only curative therapy, with improved post-2008 survival in a modern pediatric cohort. Symptomatic management includes antibiotic prophylaxis, immunoglobulin administration, and nutritional support.

Key References

  • PMID:11258423 - Molecular genetics of the Bare lymphocyte syndrome.
  • PMID:8402893 - Complementation cloning of CIITA in hereditary MHC class II deficiency.
  • PMID:9287230 - RFXAP mutations and complementation group D.
  • PMID:29527204 - Clinical, immunological, and molecular findings in five patients.
  • PMID:8229525 - Thirty-patient clinical series and natural history.
  • PMID:34211466 - Thymic epithelial and tolerance perturbation mechanisms.
  • PMID:20493394 - HSCT and symptomatic management strategies.
  • PMID:31932845 - Improved modern HCT survival and outcome.