ITGA6 and obesity due to melanocortin 4 receptor deficiency: Inbred BTBR and C57BL/6J mice were used to identify genes affecting obesity and glucose metabolism. A ∼316 kb region on chromosome 2 was studied, focusing on Pdk1 and Itga6. Knockout mice lacking Pdk1 or Itga6 were fed an obesogenic diet to assess their role in obesity and glucose tolerance.