The MBL group contains a subtype of CLL/SLL-type MBL with monoclonal CLL/SLL-phenotype B-cell count ≥0.5 x 109/L and total B-cell count less than 5 x 109/L with no other features of CLL/SLL (15). The gene discussed is SLC35B2; the disease is B-cell chronic lymphocytic leukemia.