Previous studies showed that genetic variants in the OPG locus have been associated with differences in bone mineral density (BMD; [24-33], osteoporotic fractures [28,34], bone turnover [31], bisphosphonate-induced osteonecrosis of the jaw [35], calcaneal quantitative ultrasound (velocity of sound) [36], ankylosing spondylitis development [37] and diabetic charcot neuroarthropathy [38]. Here, TNFRSF11B is linked to ankylosing spondylitis.