KSR2 and obesity due to melanocortin 4 receptor deficiency: While to date, other highly penetrant genetic forms of obesity have predominantly been associated with hyperphagia (Farooqi and O’Rahilly, 2006), KSR2 mutations are in addition associated with low BMR and reduced heart rate when tested under the same experimental conditions as individuals with other genetic forms of obesity (Farooqi et al., 2007; Greenfield et al., 2009).