Polymorphisms of the vitamin D receptor gene do not predict quantitative ultrasound of the calcaneus or hip axis length.

Quantitative ultrasound of the calcaneus and hip axis length are independent predictors of hip fracture and have a major genetic component. Polymorphisms of the vitamin D receptor gene (VDR) have been associated with variations in bone density in a number of studies. The aim of this study was to examine the role of VDR on other parameters associated with the risk of fracture. One hundred and eighty-nine pairs of healthy female dizygous twins were genotyped and had calcaneal ultrasound (broadband ultrasound attenuation and velocity of sound) and hip axis length measurements performed. Twin analysis using intraclass correlation coefficients and intrapair differences failed to find an association between the VDR polymorphisms and hip axis length or calcaneal ultrasound. Analysing the twins as a population, irrespective of twinning, also failed to find any association. The search for alternative genes influencing bone fragility should continue as a research priority.