ASSOCIATION BETWEEN MICA GENE A4 ALLELE AND ACUTE ANTERIOR UVEITIS INWHITE PATIENTS WITH AND WITHOUT HLA-B27

PURPOSE: Acute anterior uveitis is strongly associated with the HLA-B2 7 antigen and triggered by the involvement of some external factors. H owever, it is uncertain whether HLA-B27 itself or other gene(s) near t he HLA-B region in a linkage disequilibrium with HLA-B27 predispose to this uveitis. We therefore investigated microsatellite polymorphism i n the transmembrane region of the major histocompatibility complex cla ss I chain related gene A (MICA), located 47 kilobases (kb) on the cen tromeric side of the HLA-B gene on the short arm of chromosome 6 withi n 6p21.3. METHODS: We examined the following patients for MICA gene po lymorphism by means of polymerase chain reaction and subsequent automa ted fragment detection by fluorescent-based technology: 64 (37 HLA-B27 -positive and 27 HLA-B27 negative) whites with acute anterior uveitis, 74 (67 HLA-B27-negative and 7 HLA-B27-positive) ethnically matched ra ndom controls, and 36 HLA-B27-positive healthy controls. RESULTS: The microsatellite allele consisting of four repetitions of GCT/AGC (desig nated A4 allele) was present at the significantly higher phenotype fre quency (71.9%) in the patient group than in the ethnically matched ran dom control group (13.5%) (P < .0000001, corrected P < .0000001). The A4 allele was strongly linked to HLA-B27 in a white population. Howeve r, the A4 allele was also found at the significantly higher phenotype frequency (37.0%) even in the HLA-B27-negative patient group than in t he ethnically matched HLA-B27-negative control group (4.5%) (P = .0086 , corrected P = .043). CONCLUSIONS: These results suggest that the MIC A gene itself or other nearby gene(s) linked to the MICA A4 allele may be involved in the development of acute anterior uveitis in a white p opulation. (C) 1998 by Elsevier Science Inc. All rights reserved.