TCF7L2 and obesity due to melanocortin 4 receptor deficiency: Since TCF7L2 is most highly expressed in astrocytes, and since insulin signaling in astrocytes is known to co-regulate CNS glucose sensing and systemic glucose metabolism [56, 57], we next set out to characterize TCF7L2 function in hiPSC-derived astrocytes in an effort to understand its possible role in the comorbidity of BD and obesity.