An unselected CLL cohort needing first-line treatment revealed a SPEN mutation frequency of 1.8% (NCT00281918; 5/278 cases), a R/R-cohort a frequency of 3.7% (NCT01392079; 4/108 cases) and an RT-cohort a frequency of 18.5% (5/27 cases) (4, 14, 23). The gene discussed is SPEN; the disease is B-cell chronic lymphocytic leukemia.