Further research using bone marrow biopsies or infection-induced BCP-ALL mouse models [5, 6] is required to address whether and how the frequency and duration of contacts between Th-cells and BCP-ALL-cells correlate with AID expression, and whether and how other cells of the leukemic environment affect AID upregulation and BCP-ALL-cell proliferation. The gene discussed is AICDA; the disease is infection.