DUOX2 and cyclic hematopoiesis: The precise etiology of transient CH is unknown in most cases, but some medical conditions have been reported to be associated with transient CH (3, 11), including iodine deficiency (11, 17) and excess (11), maternal transfer of TSH receptor-blocking (TRAb) autoantibodies (32, 33, 34, 35), and mutations in genes that are involved in thyroid hormone biosynthesis, including DUOX2, DUOXA2 (36, 37, 38), and TSH receptor (TSHR) (39).