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N. C. Modi, M. R. Stanford, R. Vaughan, J. R. Smith, J. T. Rosenbaum, N. K. Wade, F. Mackensen, T. M. Martin, G. R. Wallace; Analysis of the PTPN22 R620W Polymorphism in Subjects With Acute Anterior Uveitis. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1716.
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A polymorphism (rs2476601) encoding the arginine to tryptophan change at amino acid 620 (R620W) of protein tyrosine phosphatase type 22 (PTPN22) is known to contribute to genetic risk of autoimmunity. This variant has been associated with several common autoimmune diseases, including Graves’ disease, rheumatoid arthritis, and type 1 diabetes, and recently found to be inversely associated with a UK cohort of Behcet’s disease. Acute anterior uveitis (AAU) is the most common form of immune-mediated uveitis, and is highly associated with HLA-B27 and spondyloarthritis. In this study, we sought to determine if PTPN22 R620W contributes to AAU.
This research was conducted under human subjects protocols approved by the OHSU and UB ethics committees. Genomic DNA was extracted from whole blood obtained from healthy controls and subjects with AAU. The diagnostic validation of AAU was based on ophthalmology chart review by JRS. Genotyping of PTPN22 R620W was performed by SSP-PCR and analysed using the Fisher’s exact test.
One hundred forty subjects with AAU (78 female, 62 male) and 92 healthy controls (54 female, 38 male) were included in the analysis. The majority of each group were Caucasian by self-report: 133/140 AAU and 81/92 controls. Of the 140 with AAU, 76 had no history of ankylosing spondylitis (AS), while 58 had a diagnosis and the remaining 6 subjects were considered to have probable or early signs of AS. The R620W variant allele frequency was 9.8% in the healthy control cohort, which was similar to a UK control cohort and other published reports. This was higher than the variant allele frequency found in the AAU group (6.5%), but this difference was not statistically significant (p=0.217). By restricting the analysis to Caucasian samples, the variant allele frequency was 11.1% and 6.8%, in controls and AAU, respectively (p=0.151). Furthermore, sub-analysis of only those AAU subjects without AS revealed no difference between controls (9.8%) and cases (9.21%, p=1.000).
In a predominantly Caucasian cohort, PTPN22 R620W does not associate with AAU. A slight trend toward an inverse relationship was noted, but this result was not statistically different. A larger cohort would be needed to determine if this observation may be significant.
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