Given the predominance of TD (~93%) in the etiology of primary permanent CH in Mexicans [17], the aim of this work was to examine whether germline small-nucleotide (NKX2-5, FOXE1, and TSHR) and CNV-type (FOXE1, PAX8, NKX2-1, PAX8, and TSHR) changes in TD-related genes play an etiological role in some Mexican CH patients lacking clinical suspicion of a syndromic form and with a confirmed TD imaging-based diagnosis. The gene discussed is PAX8; the disease is cyclic hematopoiesis.