As shown in Figure 5, human ZIP4 proteins carrying the Leu372Pro and Leu372Arg mutations showed an absence of surface protein expression (P<0.001, one way ANOVA versus the Ala357-Leu372 isoform), consistent with the known causal role of these variants in the zinc deficiency disorder, acrodermatitis enteropathica. Here, SLC39A4 is linked to acrodermatitis enteropathica.