LEP and obesity due to melanocortin 4 receptor deficiency: The disruption of the Hmga2 gene caused a dramatic reduction in obesity of the leptin-deficient mice (Lepob/Lepob) in a gene-dosage-dependent manner: Hmga2+/+ Lepob/Lepob mice weighed over three times more than Hmga2-/- Lepob/Lepob animals, and the weight of Hmga2+/- Lepob/Lepob mice was in between [60].