The response to ultraviolet light and the histologic appearance of the epidermis was studied in two brothers with histidinemia. One of the siblings demonstrated a decreased minimal erythema dose while the other more pigmented brother showed a normal response. The epidermis appeared to be normal by light and electron microscopy.
Baden HP, Hori Y, Pathak MA, Levy HL. Epidermis in Histidinemia. Arch Dermatol. 1969;100(4):432-435. doi:10.1001/archderm.1969.01610280050007