PIK3CA and obesity due to melanocortin 4 receptor deficiency: PIK3CA mutation (hazard ratio (HR): 0.61; 95% confidence interval (CI): 0.37–0.99; P=0.046), overweight (HR: 0.56; 95% CI: 0.32–0.96; P=0.033) and obesity (HR: 0.44; 95% CI: 0.20–0.95; P=0.036) were associated with a significantly lower cumulative complete response (CR) rate.