POT1 and cancer: The link between POT1 and TP53 is reinforced by the recent finding of POT1 germline mutations in three TP53-negative Li–Fraumeni-like families with cardiac angiosarcoma, a very rare malignant tumour.4 A few ATR mutations have also been described in CLL, but it is unclear whether they are mutually exclusive to POT1 (and ATM) mutations.