To exclude other causes of CH, we performed mutation analysis of the THRB gene and a gene panel for thyroidal CH, including the sequencing and copy number variance analysis of the following genes: CDCA8, DUOX1, DUOX2, DUOXA2, FOXE1, GLIS3, GNAS, HOXA3, IYD, JAG1, NKX2-1, PAX8, SLC26A4, SLC5A5, TG, TPO, TPST2 and TSHR. The gene discussed is TPO; the disease is cyclic hematopoiesis.