Low serum leptin level was observed in one obesity subject (P291) (BMI 26.3 kg/m2 with serum leptin 7.41 ng/ml) and one overweight subject (C155) (BMI 23.4 kg/m2 with serum leptin 4.36 ng/ml) (Table 3). Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.