J Clin Endocrinol Metab 99 (12): 4408 - 22, 2014. doi: 10.1210 / jc.2014 - 2910 Etiology of Paget Disease of Bone About 10% of patients with Paget disease have mutations of the SQSTM1 (sequestosome-1) gene, resulting in increased nuclear factor kappa-B activity, which increases osteoclast activity (1, 2).