G6PC1 and obesity due to melanocortin 4 receptor deficiency: Indeed, since G6Pase, mutated in GSDIa patients is expressed only in liver, bowel and kidney, we hypothesized the presence of IR without obesity as is the case of mouse model with selective liver 11β-HSD1 overexpression, showing insulin resistance, dyslipidemia, and hypertension, but unaltered adiposity.