BTK and B-cell chronic lymphocytic leukemia: Our assay targeted the complete coding regions of five most frequently mutated “CLL-genes” (ATM, MYD88, NOTCH1, SF3B1 and TP53) [6, 7, 10] and additionally ten genes with a more exploratory driven interest, e.g. the kinase domains of the drug targets BTK and PIK3CD [15].