The most commonly mutated genes in CH are DNA methyltransferase 3 alpha (DNMT3A), Tet methylcytosine dioxygenase 2 (TET2), ASXL transcriptional regulator 1 (ASXL1), Protein phosphatase, magnesium-dependent, 1, delta isoform (PPM1D), Janus kinase 2 (JAK2), and splicing factor 3b Subunit 1 (SF3B1); however, CH alterations may also include variants in TP53, Ataxia-telangiectasia mutated serine/threonine kinase (ATM), and other genes that are both frequently CH- and tumor-derived, and their source may be difficult to distinguish. The gene discussed is PPM1D; the disease is neoplasm.