73-P: STRONG ASSOCIATION BETWEEN THE IL2 (-330G/T) GENOTYPE AND CLASSIC PARS PLANITIS (CPP) IN MEXICANS

Aim Classic Pars Planitis (CPP) is a common form of intermediate uveitis of unknown etiology, characterized by a chronic mild inflammation in the anterior chamber of the eye, vitritis, retinal flebitis and snow banking at least in one eye, without any systemic associations. The prevalence of CPP is 14.8% of all uveitis seen at the Mexican Referral Center, where the study was performed. It is more frequent in male children under 14 years old. We searched for the possible participation of IL2 (-330G/T alleles and genotypes in Mexican Mestizo PP patients. Methods A total of 82 patients with PP and 278 controls, all of them Mexican Mestizo, were included. DNA was obtained from peripheral blood samples using Maxwell16 instrument (Promega). For allele discrimination of the IL2(-330G/T) rs2069762, a Taqman real time PCR assay was used on ABI 7500 Real-Time PCR System (Life Technologies Foster City, CA). Results Allele and genotype distribution was significantly deviated. The T allele (OR=2.05; CI 1.4-3.1; p=0.0004) and the TT genotype (OR=1.97; CI (1.2-3.2); p=0.007) were increased in the patients, while the G allele (OR=0.49; CI (0.3-0.7); p=0.0004) and the GG genotype (OR=0.19; CI (0.06-0.6); P=0.003) were significantly decreased. The allele distribution was under Hardy Weinberg expectation among controls. Conclusions Very scarce data exist in the literature regarding the genetics of CPP. This study shows the influence of IL2-330(G/T) genotype on the expression of CPP. Functional data regarding which allele is the high production allele are contradictory, therefore no association mechanisms can be discussed. The G allele reduces “in vivo” transcription using lymphocytes from multiple sclerosis patients but it has been related as well, to a high production of IL2 in serum. Although CPP is considered “idiopathic”, some findings show a systemic Th1 response; therefore it is plausible that an SNP changing the IL2 expression may account for the susceptibility.