Endocrine Abstracts

Graves’ (GD) hyperthyroidism induces accelerated bone turnover that leads to diminished bone mineral density (BMD). Recent studies indicate the associations between VDR gene and autoimmune diseases. The role of VDR allelic variants in predisposition to primary osteoporosis is also recognized. The authors analyzed if VDR polymorphisms: BsmI, ApaI, TaqI and FokI may predispose women with Graves’ hyperthyroidism to BMD reduction. The subjects were 75 premenopausal female Polish patients with GD aged 23-46 and 100 healthy women. BMD values were evaluated at lumbar spine (L1-L4 region) and femoral neck by dual energy X-ray absorptiometry (DEXA method). The genotyping was performed using restriction fragment length polymorphism (RFLP). The association analysis of VDR polymorphisms and haplotypes with BMD as well as SNPs and haplotypes association with Graves disease were performed. The strong linkage disequilibrium was found for: BsmI, ApaI, TaqI, that formed three the most frequent haplotypes in Graves’ women: baT (47.9%), BAt (34.9%), bAT(16.4%). The lowest mean BMD values had homozygotic women with two copies of BAt. However authors did not observe statistically significant association of analyzed haplotypes or polymorphisms with bone mineral density. The analysis of polymorphic variants distribution showed that only presence of F allele of VDR-FokI was more frequent in GD women as compared to controls (OR=1.93; 95% CI:0.97–3.84) with statistical tendency to significance (P=0.058).

Conclusions: 1. F allele of VDR-FokI polymorphism may predispose Polish women to GD.

2. BsmI, ApaI, TaqI, FokI polymorphic variants of VDR gene do not predict the risk of decreased bone mineral density induced by excess of thyroid hormones in GD.