X-linked sideroblastic anemia (XLSA) and X-linked protoporphyria (XLPP) are uncommon diseases caused by loss-of-function and gain-of-function mutations, respectively, in the erythroid form of 5-aminolevulinic acid synthetase, ALAS2, which encodes the first enzyme in heme biosynthesis. A related sideroblastic anemia is due to mutations in SLC25A38, which supplies mitochondrial glycine for ALAS2 (SLC25A38-CSA). The lack of viable animal models has limited studies on the pathophysiology …