Hematin and Porphyria

Abstract

The discovery that hematin represses induction of δ-aminolevulinic acid synthetase (ALA-S), the rate-limiting enzyme for hepatic porphyrin and heme synthesis,¹ is central to recent studies seeking to provide a means of terminating or ameliorating the acute attack of acute intermittent porphyria, porphyria variegata or hepatic coproporphyria.The induction of ALA-S in the acute attack of AIP, acute intermittent porphyria, porphyria variegata or hepatic coproporphyria markedly increases the porphyrin precursors, ALA and porphobilinogen (PBG), in liver, blood plasma and urine. The enzyme is induced because of heme deficiency in the liver secondary to the genetic partial lack of uroporphyrinogen synthetase (UPG-S) . . .