Impact of Single Nucleotide Polymorphism in the ANKRD55 Gene on Occurrence and Clinical Characteristics of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) has multifactorial etiology and numerous genetic and environmental factors have been related to an increased risk of RA. Recently, Genome-Wide Association Studies (GWAS) suggested a large number of Single Nucleotide Polymorphisms (SNPs) loci affecting the susceptibility to RA. One of these loci is rs6859219 (C>A), a functional polymorphism in the ANKRD55 gene which was associated with the expression of ANKRD55 and IL6ST. In the current study, we evaluated the possible association between rs6859219 (intronic variant) in the ANKRD55 gene with RA risk in the Iranian population.

A case-control study using 118 RA patients and 115 healthy counterparts was undertaken in order to determine rs6859219 genotypes using real-time polymerase chain reaction High-Resolution Melting (HRM) method.

There was a significant difference in the genotype and allele frequencies of rs6859219 between patients and controls (p<0.001). Logistic regression analysis demonstrates that CC genotype and C allele increased the risk of RA (OR for CC genotype= 7.12; 95%CI [3.51-15.05]/ OR for C allele=4.16; 95%CI [2.78-6.28]). Furthermore, regarding the dominant and recessive model of inheritance, RA patients indicated obvious association of the rs6859219 variant compared to healthy controls (p<0.001). Moreover, in the patient group, there was a significant correlation between C-Reactive Protein (CRP) concentration with rs6859219 polymorphism (p<0.001).

Our findings propose a substantial correlation between rs6859219 polymorphism and RA risk and clinical characteristics of this disease in the Iranian population.