FGFR1 and obesity due to melanocortin 4 receptor deficiency: In addition, adipose tissue FGFR1 mRNA and protein levels were elevated in obese subjects and Fgfr1 mRNA levels were increased in the hypothalamus of diet-induced obese (DIO) rats [1], showing that FGFR1 is a novel human obesity candidate gene that may affect metabolism and control of food intake.