SFXN1 and sideroblastic anemia: Besides one-carbon metabolism, other roles of SFXN1 in mitochondrial function have recently been reported; loss of SFXN1 compromises mitochondrial complex III and impairs respiratory chain activity, and SFXN1 is important for coenzyme Q, heme and α-ketoglutarate metabolism12; enhanced protein expression of SFXN1 contributes to an increase in iron absorption, which causes sideroblastic anemia, and SFXN1 delivers cytoplasmic Fe2+ into the mitochondria, giving rise to mitochondrial ROS synthesis and ferroptosis13.