The most prevalent form of CSA is X-linked sideroblastic anemia (OMIM #300751), which is caused by a deficiency in δ-aminolevulinic acid synthase 2 (ALAS2) [4], a pyridoxal 5′-phosphate (PLP)-dependent enzyme that catalyzes the synthesis of δ-aminolevulinic acid (δ-ALA) within the erythroid cells [5,6]. The gene discussed is ALAS2; the disease is chromosome-type aberration frequency.