 Given the many presentations and the relatively low occurrence of porphyria, patients may initially be suspected to have other, unrelated conditions.For instance, the polyneuropathy of acute porphyria may be mistaken for Guillain–Barré syndrome, and porphyria testing is commonly recommended in those situations.The non-acute porphyrias are X-linked dominant protoporphyria (XLDPP), congenital erythropoietic porphyria (CEP), porphyria cutanea tarda (PCT), and erythropoietic protoporphyria (EPP).