title: MHC class I chain related gene A (MICA) modulates the development of coeliac disease in patients with the high risk heterodimer DQA1*0501/DQB1*0201.
abstract: OBJECTIVE
  Coeliac disease (CD) is an enteropathic disorder characterised by a strong association with major histocompatibility complex (MHC) heterodimer HLA-DQ2. It has been suggested that other HLA class I genes in combination with DQ may also contribute to CD susceptibility. The aim of this study was to investigate whether other candidate genes modify the risk of developing different clinical forms of CD.
  
  
  METHODS
  We studied 133 Spanish coeliac patients, divided according to their clinical presentation into typical and atypical groups, and 116 healthy controls. All were typed by polymerase chain reaction-sequence specific primers (PCR-SSP) at HLA-B, DRB1, DQA1, and DQB1 loci and for exon 5 of the MHC class I chain related gene A (MICA).
  
  
  RESULTS
  No differences were found in the frequency of the DQA1*0501/DQB1*0201 heterodimer in either group. The risk of typical CD was significantly associated with the DR7/DQ2 haplotype (p(c)=0.02, odds ratio (OR)=3.4, ethiological fraction (EF)=0.4). Extended haplotype (EH) 8.1 (B8/DR3/DQ2) was found to be overrepresented in the atypical form compared with the typical form (p(c)=0.001, OR=4.19, EF=0.56). The trinucleotide repeat polymorphism MICA-A5.1 was found to be increased in the atypical group of patients compared with the typical group (p(c)=0.00006, OR=8.63, EF=0.81). This association was independent of linkage disequilibrium with EH8.1 as this was also found to be increased in EH8.1 negative atypical patients compared with the typical group (p(c)=0.004, OR=6.66, EF=0.56).
  
  
  CONCLUSIONS
  Our results showed that the risk of developing typical forms of CD was associated with DR7/DQ2 haplotype, and the presence of B8/DR3/DQ2 was significantly increased in atypical patients. In these, the MICA-A5.1 allele confers an additive effect to the DR3/DQ2 haplotype that may modulate the development of CD.
authors.affiliation: Department of Immunology, Hospital Central de Asturias, Oviedo, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Lopez-Vazquez
authors.forename: L
authors.initials: L
authors.lastname: Rodrigo
authors.forename: D
authors.initials: D
authors.lastname: Fuentes
authors.forename: S
authors.initials: S
authors.lastname: Riestra
authors.forename: C
authors.initials: C
authors.lastname: Bousoño
authors.forename: S
authors.initials: S
authors.lastname: Garcia-Fernandez
authors.forename: J
authors.initials: J
authors.lastname: Martinez-Borra
authors.forename: S
authors.initials: S
authors.lastname: Gonzalez
authors.forename: C
authors.initials: C
authors.lastname: Lopez-Larrea
mesh_terms: D000328:Adult; D000483:Alleles; D002446:Celiac Disease / Q000235:genetics*; D005260:Female; D005805:Genes, MHC Class I; D020022:Genetic Predisposition to Disease; D006683:HLA-DQ Antigens / Q000235:genetics*; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; D006239:Haplotypes; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006650:Histocompatibility Testing / Q000379:methods; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged
chemical_list: D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; C069050:HLA-DQA1 antigen; C069051:HLA-DQB1 antigen; D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A