What is Porphyria?

Porphyrias are a group of metabolic disorders and each of the porphyrias result due to deficiency of a specific enzyme in the heme biosynthetic pathway. These enzyme deficiencies are inherited as autosomal dominant or recessive traits (the only exception being porphyria cutanea tarda or PCT which usually is sporadic). In the causation of porphyrias, environmental, physiological and genetic factors play complex roles with their interaction to each other.

Classification of porphyrias:

Porphyrias are classified depending on the primary site of overproduction and accumulation of their respective porphyrin precursors or porphyrins, as hepatic (in liver) or erythropoietic (in the red blood corpuscles) porphyrias. But some of the porphyrias the overproduction and accumulation of their porphyrins may overlap. A common example of hepatic porphyria is PTC (porphyria cutanea tarda), which is the commonest form of porphyria and presents with blistering cutaneous photosensitivity.

The erythropoietic porphyrias usually present with cutaneous photosensitivity at birth or in early childhood and sometimes even during intrauterine life (as is the case of congenital erythropoietic porphyria or CEP). In the erythropoietic porphyrias there is excess production porphyrins due to sensitivity to sunlight, especially to long-wave ultraviolet light. This cutaneous sensitivity to sunlight cause cell damage, scarring, and deformation of skin.

The symptoms of porphyrias are generally non specific and the diagnosis of porphyria may be delayed due to this. The facilities required for diagnosis of porphyria may not be available in all the diagnostic laboratories, which also can delay the diagnosis and as a result there is delay in starting appropriate treatment of porphyria.

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