Elevated human β cell death observed in medium containing T1D serum (2.1 ± 0.18%) relative to ND serum (1.0 ± 0.11%) was significantly reduced with OPG treatment (1.4 ± 0.15%); however, OPG had no effect on basal β cell death in ND serum (1.3 ± 0.19%)–containing medium (Fig. 9C). The gene discussed is TNFRSF11B; the disease is type 1 diabetes mellitus.