NOTCH1 mutated patients have a rapidly progressive disease and a significantly shorter survival probability (21–45% at 10 years) compared to NOTCH1 wild type cases (56–66% at 10 years).10,11,14 The poor prognosis associated with NOTCH1 mutations in CLL may be explained, at least in part, by a substantial risk (~40–50%) of developing Richter syndrome.10,11,14. The gene discussed is NOTCH1; the disease is Richter syndrome.