TPO and cyclic hematopoiesis: Among the many genes, Dual-oxidase 1 (DUOX1), Dual-oxidase 2 (DUOX2), Iodotyrosine deiodinase (IYD), several solute-carrier family member genes (SLC) including SLC26A7 and SLC5A5, thyroid peroxidase (TPO), and thyroglobulin (TG) have been described the Sudanese population with CH [1].