title: MHC class I and II deficiencies.
abstract: Deficiencies of MHC complex class I or II are rare primary immunodeficiencies, both of which are inherited in an autosomal recessive pattern. MHC class II deficiency is a prototype of a disease of gene regulation. Defects in transacting regulatory factors required for expression of MHC class II genes, rather than the genes themselves, are responsible for the disease phenotype. The affected genes are known to encode 4 distinct regulatory factors controlling transcription of MHC class II genes. These transacting factors are the class II transactivator and 3 subunits of regulatory factor X (RFX): RFX containing ankyrin repeats (RFXANK), the fifth member of the RFX family (RFX5), and RFX-associated protein (RFXAP). Mutations in one of each define 4 distinct complementation groups termed A, B, C, and D, respectively. MHC class I deficiency is extremely rare and has been reported in less than 30 patients worldwide. Here we review the clinical, genetic, and molecular features that characterize these primary immunodeficiencies and discuss therapy options. Beyond the description of MHC class I and II deficiencies, their discovery has fascinated scientists and clinicians because of their ability to reveal the molecular basis of MCH regulation.
authors.affiliation: Department of Pediatrics and the Pediatric Immunology Unit, Rambam Medical Center, and the B. Rappaport Faculty of Medicine, Technion, Haifa, Israel.
authors.forename: Suheir
authors.initials: S
authors.lastname: Hanna
authors.affiliation: Department of Pediatrics and the Pediatric Immunology Unit, Rambam Medical Center, and the B. Rappaport Faculty of Medicine, Technion, Haifa, Israel. Electronic address: Etzioni@rambam.Health.gov.il.
authors.forename: Amos
authors.initials: A
authors.lastname: Etzioni
mesh_terms: D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000175:diagnosis / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; C093524:RFX5 protein, human; C117892:RFXANK protein, human; C413004:RFXAP protein, human; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors
keywords: MHC class I and II; class II transactivator; immunodeficiency; regulatory factor X; tapasin; transporter associated with antigen processing I and II