title: Microsatellite polymorphism of the MHC class I chain-related (MIC-A and MIC-B) genes marks the risk for autoimmune Addison's disease.
abstract: The major histocompatibility complex class I chain-related MIC-A and MIC-B genes are located on chromosome 6 between the histocompatibility leucocyte antigen (HLA)-B and the B-associated transcript genes. The presence of 21-hydroxylase autoantibodies is a sensitive and specific marker of autoimmune Addison's disease. We studied the polymorphism of exon 5 of the MIC-A gene, of intron 1 of the MIC-B gene, and of HLA-DRB1, -DQA1, and -DQB1 genes in 28 autoimmune (21-hydroxylase autoantibody positive) Addison's disease patients and in 75 healthy subjects from central Italy. The MIC-A5.1 allele was significantly more frequent in Addison's disease patients (79%) than in healthy subjects (36%) [odds ratio (OR) = 6.52, corrected P (Pc) = 0.0015], whereas MIC-A6 was significantly reduced in affected subjects (15% vs. 56%, OR = 0.13, Pc = 0.002). The A5.1/A5.1 genotype had an OR for autoimmune Addison's disease as high as 18.0 and an absolute risk of 1 per 1131. In the presence of MIC-A5.1, MICB-CA-25 was significantly increased in Addison's disease patients (25% vs. 4%, OR = 8.0, P = 0.0039, Pc = 0.047). The MICB-CA-17 allele was absent in Addison's disease patients, but present in more than 25% healthy individuals (OR = 0.10, P = 0.0025, Pc = 0.03). Among HLA-DR and -DQ haplotypes, only DRB1*03-DQA1*0501-DQB1*0201 (DR3/DQ2) was significantly more frequent in Addison's disease patients than in healthy subjects, but only in the presence of MIC-A5.1. The frequency of MIC-A5.1 was significantly increased in Addison's disease patients only in the presence of HLA-DR3-DQ2. Our study demonstrates that susceptibility to autoimmune Addison's disease is linked to the MIC-A microsatellite allele 5.1 and that both MIC-A5.1 and HLA-DR3/DQ2 are necessary to confer increased genetic risk for Addison's disease.
authors.affiliation: Immunology and Immunogenetics Laboratory, Department of Internal Medicine and Endocrine and Metabolic Sciences, University of Perugia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Gambelunghe
authors.forename: A
authors.initials: A
authors.lastname: Falorni
authors.forename: M
authors.initials: M
authors.lastname: Ghaderi
authors.forename: S
authors.initials: S
authors.lastname: Laureti
authors.forename: C
authors.initials: C
authors.lastname: Tortoioli
authors.forename: F
authors.initials: F
authors.lastname: Santeusanio
authors.forename: P
authors.initials: P
authors.lastname: Brunetti
authors.forename: C B
authors.initials: CB
authors.lastname: Sanjeevi
mesh_terms: D000224:Addison Disease / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000235:genetics*; D002648:Child; D005260:Female; D005805:Genes, MHC Class I / Q000235:genetics*; D005838:Genotype; D006683:HLA-DQ Antigens / Q000235:genetics; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; D006684:HLA-DR Antigens / Q000235:genetics; D059811:HLA-DRB1 Chains; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D012307:Risk Factors
chemical_list: D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; C069050:HLA-DQA1 antigen; C069051:HLA-DQB1 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A; C098080:MICB antigen