[The association of vitamin D receptor gene ApaI and BsmI polymorphism with systemic lupus erythematosus].

Objective: To determine the distribution of vitamin D receptor (VDR) gene ApaI and BsmI polymorphism in systemic lupus erythematosus (SLE) and the association with SLE in Chinese Han patients.

Methods: Genomic DNA from 244 Chinese SLE patients and 162 sex and ethnically matched controls were typed for VDR ApaI and BsmI polymorphism combination by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Clinical characteristics were analyzed between different ApaI and BsmI genotypes.

Results: There was no significant difference between the distribution frequencies of allelic gene A and a in SLE patients and the controls, but the distribution frequency of genotypes heterozygote Aa in SLE patients was higher than that in the controls (38.9% vs 22.2%, χ(2) = 12.442, P = 0.000). There was no significant difference between the distribution frequency of allelic gene and genotypes of BsmI in SLE patients and the controls (P > 0.05). However, there was significant difference between the distribution frequencies of ApaI and BsmI genotypes combination in SLE patients and the controls (χ(2) = 18.226, P = 0.006). The distribution frequency of genotypes Aa-bb in SLE patients was higher than that in the controls (32.4% vs 17.9%, χ(2) = 10.449 P = 0.001), while the distribution frequency of genotypes Aa-bb in SLE patients was lower than that in the controls (30.3% vs 42.0%, χ(2) = 5.808, P = 0.016). Furthermore, analyzing the effect of VDR ApaI and BsmI polymorphism combination to the symptoms of SLE, significant difference was observed in SLE patients carrying Aa-bb genotypes involved in serositis (P = 0.003), hematological system disorder (P = 0.021), and anti-Sm antibodies (P = 0.01) compared with other genotypes.

Conclusion: There is significant association between ApaI and BsmI gene polymorphism Aa-bb genotypes and the incidence of SLE in the Han population of China, and genotype Aa-bb is more involved in serositis, hematological system disorder and has a positive effect on production of antibodies.