UROS and ALAS-2: Erstwhile partners in crime

Abstract

Congenital erythropoietic porphyria is caused by a deficiency in uroporphrynogen III synthase, the fourth enzyme in the heme biosynthetic pathway. In this issue of Blood, To-Figueras and colleagues present convincing genetic and biochemical evidence that the clinical phenotype of the rare disorder is markedly affected by the coinheritance of an activating mutation in the erythroid-specific isoform of δ-aminolevulinic acid synthase.