Hepatoerythropoietic porphyria
Hepatoerythropoietic porphyria is a very rare form of hepatic porphyria caused by a disorder in both genes which code Uroporphyrinogen III decarboxylase.
It has a similar presentation to porphyria cutanea tarda, but with earlier onset. In classifications which define PCT type 1 as "sporadic" and PCT type 2 as "familial", hepatoerythropoietic porphyria is more similar to type 2.