Fasting plasma leptin levels were similar among PWS patients in nutritional phase 1a, 1b and 2a, however, the transition from phase 2a to phase 2b was associated with a significant increase in plasma leptin (613 ± 265 vs. 2328 ± 467; p = 0.009) (Figure 1D; Table 2). The gene discussed is LEP; the disease is Prader-Willi syndrome.