BDNF and obesity due to melanocortin 4 receptor deficiency: Human studies have revealed association of the val66met BDNF polymorphism with obesity, suggesting a clinical role for BDNF signaling in feeding and body weight regulation (Marques-Iturria et al., 2014; Martinez-Ezquerro et al., 2017; Goldfield et al., 2021), and this finding has recently been recapitulated in a mouse model (Ieraci et al., 2020).