The importance of the BCR in the CLL microenvironment is shown by the revolutionary effects of phosphatidylinositol 3 kinase (PI3K) δ inhibitors such as idelalisib and duvelisib and BTK inhibitors, such as ibrutinib, acalabrutinib and zanubrutinib (68). The gene discussed is BCR; the disease is B-cell chronic lymphocytic leukemia.