Given that Tfr1Adp/Adp mice have significantly lower iron levels in both iWAT and iBAT, we next tested whether iron deficiency plays a causal role in the phenotypes observed in Tfr1Adp/Adp mice using a genetic mouse model of iron deficiency (Tmprss6−/− mice),[22] We first confirmed that Tmprss6−/− mice lack hepcidin repressor matriptase‐2 (encoded by the Tmprss6 gene) and have both increased hepcidin expression (Figure S7A, Supporting Information) and reduced iron levels (Figure6A) compared to control mice. The gene discussed is HAMP; the disease is nutritional disorder.