Objective: The aim of this study was to assess the possible association between the interleukin-12B (IL12B) and interleukin-12 receptor beta 1 (IL12RB1) gene polymorphisms with systemic lupus erythematosus (SLE). In addition, we have undertaken a systematic search for genetic variants of interleukin 23 (IL23A).
Methods: The study was conducted on 559 SLE patients and 603 ethnically matched healthy controls. Genotyping of the IL12B [IL12Bpro and IL12B 3' untranslated region (UTR)] and IL12RB1 (641A-->G, 1094T-->C and 1132G-->C) polymorphisms was performed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR-fluorescent methods, whereas IL23A genetic variants were realized with direct sequencing.
Results: No statistically significant differences in the distribution of the IL12B and the IL12RB1 genotypes and alleles were observed when comparing SLE patients and control subjects. Additionally, no differences in the genotype and allele distribution were found when SLE patients were stratified according to the presence or absence of lupus nephritis. Despite an extensive analysis in 30 individuals, variations located in the exons and in the 5' and 3' UTR regions of IL23A gene were not found in any case.
Conclusions: These results suggest that polymorphisms located in IL12B, IL12RB1 and IL23A genes may not play a relevant role in the susceptibility or severity of SLE in the Spanish population.