SLC40A1 and hemochromatosis type 4: and the human SLC40A1 protein (p.), also considering the protein structure (TM: transmembrane helices and ECL or ICL: extra- or intracellular loops), (ii) reported functional effect (loss-of-function, gain-of-function, and neutral), (iii) ACMG/AMP classification, and (iv) relationship with clinical phenotypes (ferroportin disease, hemochromatosis type 4, and unexplained hyperferritinemia).