[The porphyria cutanea tarda group: their role among the enzyme defects of heme biosynthesis].

Porphyria cutanea tarda (PCT) is the most common porphyria. In contrast to the other porphyrias, which are undisputably hereditary, PCT was long considered to be acquired. However, the recent demonstration of a defect in uroporphyrinogen decarboxylase suggests that PCT is supported by a genetic factor. Though the hereditary or acquired nature of the enzymatic defect is still under debate, it seems that the disease has a polygenic origin involving an impairment of iron metabolism and a specific genetic background.