SLC40A1 and Tangier disease: As an iron exporter, FPN plays a critical role in cellular iron release.[28] FPN mutation (loss‐of‐function) reduced iron export from cells, which appears to be one of the common causes of hereditary iron overload.[29] In consistence, Huwe1 cKO mice with low expression of Fpn exhibited more iron accumulation (Figure 2K; Figure S4J,K, Supporting Information).