Vitamin-D receptor genotype and renal disorder in Japanese patients with systemic lupus erythematosus

Background/Aims: It is known that allelic variants of the gene encoding the vitamin-D receptor (VDR) detected by BsmI increase the risk of some advanc ed malignant tumors, suggesting that such variants may cause functional dif ferences in 1,25(OH)(2) vitamin D-3. We examined the VDR genes of Japanese systemic lupus erythematosus (SLE) patients, to determine whether different genotypes are correlated with SLE or its criteria. Methods: VDR genotyping of 58 unrelated Japanese SLE patients was performed based on polymerase ch ain reaction-restriction fragment length polymorphism (RFLP). Following amp lification, products were digested with BsmI. The RFLPs were coded as Bb, w here the uppercase letter signifies the absence of the digested site and th e lowercase letter signifies the presence of the site. Results: The frequen cy of the VDR BB genotype was significantly higher in SLE patients (15.5%, n = 9/58, p < 0.0001) than in controls (5.7%, n = 5/87), Furthermore, a lar ger proportion of bb individuals was observed among patients with nephrotic syndrome (61.5%, n = 8/13) than among SLE patients without renal dysfuncti on (35.7%, n = 10/28). There was a significant tendency for the population of patients with the bb genotype to be correlated with that of patients wit h renal dysfunction (p = 0.0304), Conclusion: These findings suggest that t he BB genotype might trigger the development of SLE, and that the bb genoty pe is associated with lupus nephritis. Copyright (C) 2000 S. Karger AG, Bas el.