Recent studies have identified genetic defects associated with CH, with more than 40 associated genes, including TSHR, TITF2, NKX2 (TITF1), PAX8, NKX2-5, DUOX2, GLIS3, TUBB1, CDCA8, JAG1, HHEX, HES1, HOXA3, EYA1, TPO, SLC5A5, DUOX1, DUOXA2, SLC26A4, TG, TRHR, TSHB, IGSF1, HESX1, TBL1X, IYD, LEPR, PROP1, POU1F1, LHX3, andLHX4, among others (14). Here, TPO is linked to cyclic hematopoiesis.