Solved cases usually had a more severe phenotype than unsolved or ambiguous cases; however, the latter group included four cases of subclinical or mild CH harboring heterozygous mutations in TPO or TG. Such monoallelic mutations have previously been described in association with CH, but are usually assumed to coexist with an additional undetected CNV, intronic, or regulatory mutation on the other chromosome (16, 24, 29). This evidence concerns the gene TPO and cyclic hematopoiesis.