AB0002 ASSOCIATION OF C1Q GENETIC POLYMORPHISMS WITH SUSCEPTIBILITY TO RHEUMATOID ARTHRITIS IN BULGARIAN COHORT
Authors: M. Kosturkova, G. Mihaylova, M. Radanova
Journal: Annals of the Rheumatic Diseases (2021)

Background: Complement is strongly implicated in the pathogenesis of autoimmune diseases like systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Its component C1q plays a dualistic role, triggering the inflammatory cascade on one hand and directing the clearance of immune complexes on the other. Homozygous genetic deficiency of C1q is strongly associated with SLE and SLE-like phenotype as almost 90% of C1q deficient individuals develop SLE or similar disease. Nevertheless, there are few and inconsistent studies exploring the single nucleotide polymorphisms (SNPs) of the C1q gene cluster in relation to the pathogenesis of SLE and RA. Objectives: The aim of the study was to evaluate the possible association of five SNPs – rs292001, rs172378, rs294179, rs665691 and rs682658 in complement C1q gene cluster with susceptibility to SLE and RA in Bulgarian cohort. Methods: Fifty patients with SLE, sixty-one patients with RA and sixty-seven healthy controls were genotyped for the five SNPs by TaqMan allelic discrimination assay. Results: Frequency of genotypes and alleles of rs294179, rs665691 and rs682658 SNPs was similar between patients with SLE, RA and healthy controls. For rs172378 SNP, the minor G allele (OR = 2.73; 95% CI, 1.59-4.67, p=0.0003) and GG genotype (OR = 5.12; 95% CI, 1.60-16.49, p=0.006) were associated with susceptibility to RA. In our cohort in accordance with others, AA rs292001 SNP genotype was associated with increased risk for RA (OR = 3.32; 95% CI, 1.19-9.20, p=0.021). For SLE patients, AA rs292001 SNP genotype was low presented and did not associate with disease. Conclusion: GG genotype of rs172378 SNP in C1q gene cluster could be considered as a new risk factor for RA. References: [1]Diane Scott et al (2016). The paradoxical roles of C1q and C3 in autoimmunity. Immunobiology, 719-25. doi:10.1016/j.imbio.2015.05.001. [2]Giles JL et al (2015). Functional analysis of a complement polymorphism (rs17611) associated with rheumatoid arthritis. J Immunol., 3029-34. doi:10.4049/jimmunol.1402956. [3]Holers, V. M. (2018). Complement in the Initiation and Evolution of Rheumatoid Arthritis. Frontiers in immunology, 1057. doi:10.3389/fimmu.2018.01057. [4]Lintner, K. E. (2016). Early Components of the Complement Classical Activation Pathway in Human Systemic Autoimmune Diseases. Frontiers in immunology, 36. doi:10.3389/fimmu.2016.00036. [5]Lu, J. &amp;. (2017). C1 Complex: An Adaptable Proteolytic Module for Complement and Non-Complement Functions. Frontiers in immunology, 592. doi:10.3389/fimmu.2017.00592. [6]Manderson, A. P. (2004). The role of complement in the development of systemic lupus erythematosus. Annual review of immunology, 431-456. doi:10.1146/annurev.immunol.22.012703.104549. [7]Martens, H. A. (2009). Analysis of C1q polymorphisms suggests association with systemic lupus erythematosus, serum C1q and CH50 levels and disease severity. Annals of the rheumatic diseases, 715–720. doi:10.1136/ard.2007.085688. [8]Namjou B, G.-M. C. (2009). Evaluation of C1q genomic region in minority racial groups of lupus. Genes Immun., 517-24. doi:10.1038/gene.2009.33. [9]Radanova M et al(2015). Association of rs172378 C1q gene cluster polymorphism with lupus nephritis in Bulgarian patients. Lupus, 280-9. doi:10.1177/0961203314555173. [10]Rafiq S et al (2010). Assessing association of common variation in the C1Q gene cluster with systemic lupus erythematosus. Clin Exp Immunol., 284-9. doi:10.1111/j.1365-2249.2010.04185.x. [11]Schejbel L et al (2011). Molecular basis of hereditary C1q deficiency-revisited: identification of several novel disease-causing mutations. Genes Immun., 626-634. [12]Trouw LA et al (2013). Genetic variants in the region of the C1q genes are associated with rheumatoid arthritis. Clin Exp Immunol., 76-83. doi:10.1111/cei.12097. [13]Trouw L. A. (2017). The complement system as a potential therapeutic target in rheumatic disease. Nature reviews. Rheumatology, 538–547. doi:10.1038/nrrheum.2017.125. [14]Walport M. J. (2002). Complement and systemic lupus erythematosus. Arthritis research, S279–S293. doi:10.1186/ar586. Disclosure of Interests: None declared