Association of FOXJ1 polymorphisms with systemic lupus erythematosus and rheumatoid arthritis in Korean population

The forkhead-box J1 (FOXJ1) transcription factor could suppress a spontaneous activation of T cells and B cells through an induction of IκBβ that results in repression of NF-κB activity. In Foxj1 deficiency mice, systemic autoimmune inflammation is quite common symptom. Therefore, deregulated Foxj1 is supposed to be associated with autoimmune diseases and/or other inflammatory diseases. Previously, we identified that polymorphisms of human FOXJ1 gene (g.-460C>T, g.1805G>T and g.3375G>C) are associated with allergic rhinitis in a Korean population. In present study, we compared the genotype and allele frequencies of these SNPs between healthy controls and systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA) patients. We also investigated the relationships between each genotype and the expression levels of anti-nuclear antibodies in SLE patients, and rheumatoid factor and anti-cyclic citrullinated peptide in RA patients. The frequencies of haplotypes constructed by these FOXJ1 SNPs were compared between controls and SLE (or RA) patients. The results of genotype and allele analysis showed that the prevalence of polymorphism g.3375G>C was associated with the susceptibility of SLE (P = 0.0072 and 0.0042, respectively). But no significant association was found with RA. In the haplotype analysis, however, the main CGG showed a weak association between controls and RA patients (P = 0.048).