GNPDA2 and obesity due to melanocortin 4 receptor deficiency: The variations of GNPDA2 were also found to be associated with BMI or risk of obesity in children and old age population (Elks et al., 2010; Mejía-Benítez et al., 2013; Murphy et al., 2013; Xi et al., 2013a; Pillay et al., 2015).