Low-density lipoprotein receptor-related protein 5 and vitamin D receptor gene polymorphisms in relation to vitamin D levels in menopause.

BACKGROUND

The low-density lipoprotein receptor-related protein 5 (LRP5) gene has been recently identified as a novel candidate for osteoporosis. The c.4037C>T polymorphism in the LRP5 gene has been associated with bone mass variance in general population. In contrast, the IVS8+443G>A polymorphism in the vitamin D receptor gene (VDR) has not been investigated in relation to bone metabolism. The aim of the present study was to determine VDR IVS8+443G>A and LRP5 c.4037C>T polymorphisms in a cohort of 165 perimenopausal women and to associate the genotypes with biochemical and densitometric bone parameters in a subset of 112 postmenopausal women.

METHODS

Both polymorphisms were assessed by restriction analysis of the PCR product. Calcium, parathyroid hormone, vitamin D metabolites and bone mineral density (BMD, g/cm(2)) at the hip and in the spine (L(1)-L(4)) were examined.

RESULTS

The genotype frequencies of both IVS8+443G>A (UU 75.2%, Uu 23%, uu 1.8%) and c.4037C>T (CC 73.9% TC 23.6%, TT 2.4%) were comparable to other Caucasian female cohorts. Serum 25OH vitamin D levels, assessed in only 63 probands, were significantly associated with VDR genotypes (ANCOVA, p<or=0.0027). We did not find any associations between LRP5 genotypes and bone or hormonal characteristics.

CONCLUSIONS

VDR IVS8+443G>A polymorphism was significantly associated with circulating 25OH vitamin D in postmenopausal Caucasian women. The role of candidate gene polymorphisms in the vitamin D metabolic pathway requires further investigation.