AB0010 THE ASSOCIATION OF THE LTA AND PTPN22 GENES POLYMORPHIC VARIANTS WITH THE REDUCED IMMUNOGLOBULIN A LEVEL IN PATIENTS WITH JUVENILE IDIOPATHIC ARTHRITIS

Background: Data from a number of studies indicate the presence of a genetic predisposition to the level of immunoglobulins [1]. The aberration in the distribution of serum immunoglobulin A (IgA) concentrations was previously shown in patients with juvenile idiopathic arthritis (JIA) [2]. Objectives: The goal of the study was to determine whether the LTA rs909253 and PTPN22 rs2476601 polymorphic loci variants are associated with the reduced IgA level in JIA patients. Methods: The study included 234 JIA patients (154 girls and 80 boys) from the Republic of Bashkortostan, Russia. IgA levels were measured in serum by the radial immunodiffusion method and considered reduced when they were less than the lower limit of established age-dependent reference intervals. Genotyping was performed by the real-time PCR method, and statistical processing of the results – using the two-tailed Fisher exact test (p) and the odds ratio (OR) with a 95% confidence interval (CI). Results: Reduced IgA levels were detected in 10.68% of patients with JIA (n=25), and the majority of them were girls (n=21). There were only four boys with the reduced IgA level, and therefore the isolated analysis was not carried out for them. The analysis of the LTA rs909253 polymorphic locus in the general JIA group, as well as in girls with JIA, showed that, in the presence of the reduced IgA level, the heterozygous genotype LTA rs909253*AG was significantly less common than in the absence of this IgA level abnormality (the general JIA group: 20.00% vs. 48.33%, p=0.010, OR=0.267, 95% CI 0.107-0.712; girls with JIA: 19.05% vs. 45.11%, p=0.031, OR=0.286, 95% CI 0.101-0.843, respectively). When studying the PTPN22 rs2476601 polymorphic locus in the general JIA group, the risk markers for the formation of the reduced IgA level were not established (p>0.1). At the same time, it turned out that in girls with JIA with the reduced IgA level, the genotype PTPN22 rs2476601*GG was significantly more common, and the allele PTPN22 rs2476601*A was significantly less common than in girls with JIA with normal or elevated IgA levels (*GG: 95.24% vs. 73.68%, p=0.028, OR=7.143, 95% CI 1.162-76.405; *A: 2.38% vs. 14.66%, p=0.025, OR=0.142, 95% CI 0.014–0.865, respectively). Conclusion: As a result of the study, the association of the LTA rs909253 and PTPN22 rs2476601 polymorphic loci variants with the reduced IgA level in girls with JIA was established. References [1] Jonsson S, Sveinbjornsson G, de Lapuente Portilla AL, et al. Identification of sequence variants influencing immunoglobulin levels. Nat Genet. 2017Aug;49(8):1182-1191. [2] Cassidy JT, Petty RE, Sullivan DB. Abnormalities in the distribution of serum immunoglobulin concentrations in juvenile rheumatoid arthritis. J Clin Invest. 1973Aug;52(8):1931-1936. Disclosure of Interests: None declared