(pro″to-por-fir´e-ә) erythropoietic p. erythropoietic protoporphyria(EPP) an autosomal dominant disorder, a form of erythropoietic porphyria, characterized by increased levels of protoporphyrin in the erythrocytes, plasma, liver, and feces and a wide variety ... Found on http://www.encyclo.co.uk/local/21001