However, similar to the Kir2.1 mice with lowered PVH neuron activity and obesity development, NachBac mice gained significantly more body weight compared to controls (Fig. 3d) and by 8 weeks after AAV delivery, these mice had a net weight gain of nearly 15 g relative to controls (Fig. 3e), suggesting rapid obesity development. The gene discussed is KCNJ2; the disease is obesity due to melanocortin 4 receptor deficiency.