To the Editor.—
As Drs. Johnson and Fusaro have suggested, the name "protoporphyria," for the disease heretofore called erythropoietic protoporphyria or erythrohepatic protoporphyria, is most appropriate. I would certainly agree that the change in nomenclature first proposed by Schmid and Marver1 and now supported by Drs. Johnson and Fusaro is a step in the direction of clarifying the classification of the porphyrias.I would hope that because of my acceptance of this change in nomenclature, the reader does not think that I have accepted the premise that the disease is solely of erythropoietic origin. It would be presumptuous of scientific investigators to conclude on the basis of negative study that something is universally true. In this instance, the authors have proposed that the excess protoporphyrin is derived from several different erythropoietic pools, without having performed direct studies on other porphyrin producing tissues. To determine whether their interpretation is correct,