DUOX2 and cyclic hematopoiesis: Studies on the prognosis of DUOX2 variants vary by race and country; however, CHT caused by DUOX2 variants manifests as mild CH and tends to be transient.[14,16,27] Compared to DUOX2, TG variants cause consistent PCH with a spectrum of various clinical presentations.[28] Meanwhile, in the patient group with initial TSH < 50 mIU/L at the time of diagnosis, there were relatively many patients with TSHR variants; their clinical manifestations were diverse and they were classified as either PCH or ACH.