To test whether enhanced expression of barr1 in beta-cells might ameliorate the metabolic deficits associated with obesity, we generated a transgenic mouse line that overexpressed barr1 in beta-cells under the transcriptional control of the rat insulin promoter II (RIPII-barr1 mice; Supplementary Fig. 9a). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.