Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme biosynthetic pathway (also called porphyrin pathway). They are broadly classified as acute (hepatic) porphyrias and cutaneous (erythropoietic) porphyrias, based on the site of the overproduction and accumulation of the porphyrins (or their chemical precursors). They manifest with either neurological complications or with skin problems (or occasionally both). A clinically induced and histologically identical condition is called pseudoporphyria. Pseudoporphyria is characterized by normal serum and urine porphyrin levels. The term derives from the Greek , porphyra, meaning "purple pigment". The name is likely to have been a reference to the purple discolouration of feces and urine in patients during an attack.