CLDN4 and Darier disease: In line with our findings, Raiko et al. found similar patterns of claudin-4 expression in acantholytic skin disorders such as Hailey–Hailey disease and Darier’s disease, revealing that claudin-4 localizes to the upper epidermis and acantholytic cells within Hailey–Hailey blisters and Darier’s disease [12].