In addition to confounding by indication, multiple drugs are unique to different diseases (eg, Bruton tyrosine kinase inhibitors in CLL, BCR-ABL inhibitors in CML, and multiple drugs in myeloma) and vary from highly to not immunosuppressive, and the frequency of use was too low to compare drugs within a given disease. The gene discussed is BTK; the disease is B-cell chronic lymphocytic leukemia.