TTF2 and cyclic hematopoiesis: Based on our literature review, we designed a target sequencing panel, which included 13 causative genes: DUOX2, TG, TPO, TSHR, TTF1, TTF2, PAX8, NKX2-5, GNAS, THRA, TSHB, IYD, and SLC5A5. Among 106 CH infants, 69 (65.1%) had more than one gene mutation, and a total of 132 mutations were identified in nine genes (DUOX2, TG, TPO, TSHR, TTF1, TTF2, NKX2-5, PAX8, and GNAS).