Search for a rare disease

* (*) mandatory field

Other search option(s)

Suggest an update

(*) Required fields.


Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Orphanet doesn't provide personalised answers. To get in touch with the Orphanet team, please contact

Information provided in your contribution (including your email address) will be stocked in .CSV files that will be sent as an email to Orphanet's teams. These emails might be conserved in the teams' mailboxes, in our backoffice servers but will not be registered in our databases (for more information see our section General Data Protection Regulation and data privacy (GDPR) and Confidentiality).

Captcha image

Immunodeficiency by defective expression of MHC class II

Disease definition

A rare autosomal recessive primary immunodeficiency characterized by absence of HLA class II molecules on the surface of immune cells, leading to severely impaired cellular and humoral immune response to foreign antigens, severe CD4+ T-cell lymphopenia, and hypogammaglobulinemia. The disease clinically manifests with early onset of severe and recurrent infections mainly of the respiratory and gastrointestinal tract, protracted diarrhea with failure to thrive, and autoimmune disease, and is frequently fatal in childhood.


Classification level: Disorder
  • Synonym(s):
    • Bare lymphocyte syndrome type 2
    • MHC class II deficiency
  • Prevalence: Unknown
  • Inheritance: Autosomal recessive 
  • Age of onset: Infancy, Neonatal
  • ICD-10: D81.7
  • ICD-11: 4A01.12 
  • OMIM: 209920
  • UMLS: C2931418
  • MeSH: -
  • GARD: 824
  • MedDRA: -
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.