ALAS2 and hyperinsulinemic hypoglycemia, familial, 4: The non-syndromic forms of congenital sideroblastic anemias are related to abnormalities in the genes for heme metabolism (ALAS2: XLSA form, SLC25A38: SLC25A38 deficiency form) and, more rarely, to mutations in the Fe-S cluster biogenesis protein (GLRX5: GLRX5 deficiency form; HSPA9: HSPA9 deficiency form; HSCB: HSCB deficiency form) [17,18,19] (Figure 1).