Late presentation of erythropoietic protoporphyria: case report and genetic analysis of family members.

Erythropoietic protoporphyria (EPP) is an inherited disorder of haem biosynthesis caused by decreased activity of the enzyme ferrochelatase (FECH), which catalyses the insertion of iron into protoporphyrin, the last step in haem biosynthesis. Development of clinically overt EPP usually requires inheritance of a severe FECH mutation trans to a low-expression FECH variant (FECH IVS3-48C), which is present in 13% of the U.K. population. Reduced FECH activity leads to accumulation of protoporphyrin in various tissues. An excess amount of free protoporphyrin in the skin causes photosensitivity. EPP usually presents in early childhood or infancy, with painful burning and pruritus within minutes of light exposure. Onset of symptoms in adults is rare and often associated with acquired somatic mutation of the FECH gene secondary to haematological malignancy. Here we describe a patient with EPP, in whom the presenting clinical symptom, night-time itch, did not appear until middle age and who had an asymptomatic sister with the same FECH genotype.