Subclonal p53 mutations have been observed at varying frequencies in different cancer types, including lung (Jamal-Hanjani et al. 2017), skin (Albibas et al. 2018), and chronic lymphocytic leukemia (Nadeu et al. 2016), although a study of nine major cancer types showed that ∼95% of tumors are clonal for p53 mutations (McGranahan et al. 2015). The gene discussed is TP53; the disease is B-cell chronic lymphocytic leukemia.