Meta-analysis of associations between functional prolactin −1149 G/T polymorphism and susceptibility to rheumatoid arthritis and systemic lupus erythematosus

The aim of this study was to determine whether the prolactin −1149 G/T polymorphism confers susceptibility to systemic lupus erythematous (SLE) and rheumatoid arthritis (RA). A meta-analysis was conducted for examining the associations between prolactin −1149 G/T polymorphism and susceptibility to SLE or RA using allele contrast, recessive and dominant models, and homozygote contrast. A total of 10 comparative studies, consisting of 4 SLE and 6 RA studies, involving 4252 patients and 4949 controls, were included in the meta-analysis. No association between the prolactin −1149 G allele and SLE was found when all study subjects were considered together (OR = 1.019, 95 % CI = 1.841–1.236, p = 0.845). Stratification by ethnicity also indicated no association between the prolactin G allele and SLE in either Caucasian or Latin American populations. In contrast, a significant association was observed between the prolactin G allele and RA in all subjects (OR = 1.123, 95 % CI = 1.052–1.198, p = 4.6 × 10⁻⁵). After stratification by ethnicity, the G allele was found to be significantly associated with RA in Caucasians (OR = 1.112, 95 % CI = 1.041–1.189, p = 0.002). Furthermore, the prolactin −1149 G/T polymorphism was found to be associated with RA in Caucasians under the dominant model and under homozygote contrast. This meta-analysis demonstrates that the prolactin −1149 G/T polymorphism is associated with susceptibility to RA, but not SLE, in Caucasians.