LAUSR

The objective of this study was to determine the association of the CD40LG 3′-UTR (CA)n microsatellite with rheumatoid arthritis (RA) and CD40LG mRNA levels in females from western Mexico. A case-control study with 219 RA patients and 175 control subjects (CS) was conducted. Genotyping was performed by polymerase chain reaction (PCR), X2 test was used to compare genotype and allele frequencies, and odds ratios and 95% confidence intervals were calculated to evaluate the association between RA and the microsatellite. CD40LG mRNA expression was assessed by real-time quantitative PCR. For comparisons between groups, Kruskal-Wallis or Mann-Whitney U tests for non-parametric data and ANOVA test for parametric data were performed. Among the 13 different alleles identified, CA25 was the most represented (45.4% RA and 46.3% CS). Stratification according to CA repeats as CA25 showed a tendency towards a higher frequency of >CA25 alleles in RA patients (29%) compared to CS (23.4%). There was no association between any genotype and the clinical parameters of RA patients. According to the 2-∆∆Cq method, CD40LG mRNA expression in RA patients was 4.5-fold higher compared to CS; this difference was significant when assessed by the 2-∆Cq method (p = 0.028). Compared to carriers of the CA25/CA25 genotype, CS carrying the CA25/>CA25 carriers. The 3′-UTR CD40LG (CA)n microsatellite is not a genetic marker for RA in western Mexican population; however, results suggest that it plays a role in the CD40LG mRNA expression.