ALAS1 and blood disease: As a result, aberrations inany step of heme biosynthesis during late erythropoiesis can resultin several blood diseases.2−5 Aminolevulinic acid synthase (ALAS) catalyzes thefirst and rate-limiting step of heme biosynthesis, in which glycineand succinyl-CoA condense into aminolevulinic acid (ALA).6−9 ALAS is conserved among α-proteobacteria and nonplant eukaryotes,where it is transported to the mitochondrial matrix to initiate hemebiosynthesis (reviewed in ref (10)).