VDR and intervertebral disk degenerative disorder: The need to perform functional studies to analyze the effects of vitamin D on the fibro-cartilaginous disc and the osteo-cartilaginous endplate (CEP) resides in a number of evidences describing the association between the four most studied, known genetic VDR variants (FokI, BsmI, TaqI and ApaI), and the disc degeneration-related pathologies [3,4], although inconsistent associations have been reported [5,6].