FECH and erythropoietic protoporphyria: In this early study, ALA-induced PpIX was much higher in lymphocytes from erythropoietic protoporphyria patients (carrying the loss-of-function mutation of the FECH gene) than in normal human lymphocytes and could be further enhanced by an iron chelator, suggesting the importance of FECH and ferrous iron in regulating PpIX level.