Although we did not examine the competition of iron between adipocytes and ATM, it is reasonable to assume that reduced adipocyte browning in obesity (or beige fat differentiation) could stem from 1) the lack of available iron for beige precursor cells to differentiate into adipocytes due to sequestration of iron into ATM and 2) unable to import iron into beige adipocytes due to lack of iron transporter, TfR1. The gene discussed is ATM; the disease is obesity due to melanocortin 4 receptor deficiency.