Two Sanger sequencing-based reports found that heterozygous loss-of-function PAX8 genotypes account for the etiology of ~1% of Mexican CH-TD patients [18], and that clearly deleterious small nucleotide changes in NKX2-1 did not appear to be a factor in this population [19]. The gene discussed is NKX2-1; the disease is cyclic hematopoiesis.