Aminolevulinate Delta Synthase 2 (ALAS2)

ALAS2 catalyzes the first step in the heme biosynthetic pathway. Defects in this gene cause X-linked pyridoxine-responsive sideroblastic anemia. Alternatively spliced transcript variants encoding different isoforms have been identified.Two forms of ALAS exist in humans: a housekeeping form encoded by the ALAS1 gene  and an erythroid tissue-specific form encoded by the ALAS2 gene (Bishop et al., 1990).Astrin and Bishop (1989) isolated the ALAS2 gene from an erythroid human fetal liver library. ALAS2 appeared to be expressed only in erythroid cells.Surinya et al. (1998) determined that the ALAS2 gene spans about 35 kb and contains 11 exons. An erythroid-specific enhancer in intron 8 contains GATA and CACCC boxes that are conserved in mouse and canine Alas2.