2007). If hypocalcemia persists, intracellular PTH degradation rate declines within 20 min, thereby increasing the amount of intact PTH that can be released (Schwarz et al. 1993). If normocalcemia is still not attained, the PTH production rate increases within an hour (Habener 1981). Subsequently, the PTG will augment its cellular proliferation rate within 2 days (Tokumoto et al. 2005). In chronic hypocalcemia, the enhanced proliferation rate will lead to hyperplasia whereby the PTG mass increases 10–100 fold or more (Fukagawa et al. 2006) (Fig. 1). The gene discussed is PTH; the disease is Hypocalcemia.