The role of BsmI and FokI vitamin D receptor gene polymorphisms and serum 25-hydroxyvitamin D in Brazilian patients with systemic lupus erythematosus.

Vitamin D deficiency has been described in systemic lupus erythematosus (SLE). BsmI VDR (vitamin D receptor) gene polymorphism was associated with SLE in Asian patients. Studies in Brazilian populations have not been realized. A case-control study with 195 SLE patients and 201 healthy controls was conducted to investigate the influence of BsmI and FokI VDR gene polymorphisms on susceptibility to SLE. In addition, 25-hydroxyvitamin D [25(OH)D] was measured in SLE patients to evaluate possible associations with VDR polymorphic variants and clinical and laboratory expressions of disease. Genotyping was performed by RFLP-PCR. The measurement of 25(OH)D was performed by chemiluminescence. There was no statistically significant difference in genotype and allelic frequencies of BsmI and FokI polymorphisms between European-derived cases and controls. The mean serum levels of 25(OH)D were 25.51 ± 11.43 ng/ml in SLE patients. According to genotype distribution, 25(OH)D concentrations were significantly higher in patients carrying the FokI f/f genotype compared with patients carrying the F/F genotype (31.6 ± 14.1 ng/ml versus 23.0 ± 9.2 ng/ml, p = 0.004), reinforcing its role in the functional activity of VDR. This feature may be considered in future clinical and experimental studies involving vitamin D measurements. Therefore, genetic-specific definitions of ideal levels of vitamin D in SLE need to be established in future studies.

Mannose-binding lectin gene polymorphisms in Brazilian patients with systemic lupus erythematosus.

The mannose-binding lectin gene (MBL-2) has emerged as a candidate for systemic lupus erythematosus susceptibility, but studies in Brazilian population have not been conducted. To examine potential associations of mannose-binding lectin alleles G57E, G54D, IVSnt5, R52C and R52H with susceptibility to and clinical expression of systemic lupus erythematosus in southern Brazilian patients, we conducted a case-control study with 327 consecutive patients with diagnosis of systemic lupus erythematosus and 345 healthy controls. Genotyping was performed by restriction fragment length polymorphism-polymerase chain reaction assay. A statistically significant difference in the frequencies of allele R52C was observed in European-derived systemic lupus erythematosus patients when compared with controls (9.6% vs. 3.3%, p < 0.001, odds ratio: 3.15, 95% confidence interval: 1.76-5.62, p < 0.05). The frequencies of alleles G54D and G57E were not different between European-derived systemic lupus erythematosus patients and controls. There were no differences between clinical and laboratory features in systemic lupus erythematosus patients according to the presence or absence of mannose-binding lectin allelic variants. These results support an increased risk of systemic lupus erythematosus in European-derived individuals carrying allele R52C. Patients carrying this allele have an approximately three-fold higher odds ratio of developing systemic lupus erythematosus when compared with controls. Our data do not support associations between the mannose-binding lectin allelic variants studied and clinical expression of systemic lupus erythematosus.