through functional studies in vivo revealed that hemizygous loss of ID4 in non‐transformed TCL1‐positive B cells enhanced cell proliferation triggered by CpG oligonucleotides and decreases sensitivity to dexamethasone‐mediated apoptosis in chronic lymphocytic leukaemia (CLL) 40. The gene discussed is ID4; the disease is B-cell chronic lymphocytic leukemia.