High bone turnover rates are associated with osteoporosis when osteoblasts cannot compensate for osteoclast activity, particularly in the setting of estrogen deficiency and Polg mice are known to display gonadal atrophy as early as 12 weeks of age (Trifunovic et al., 2004; Kujoth et al., 2005; Weitzmann, 2006). The gene discussed is POLG; the disease is osteoporosis.