Besides CLL-type MBL, atypical CLL (CD5 + /bright CD20 + /variable CD23 + /bright surface immunoglobulin) and non-CLL (CD5-dim/negative without other phenotypic markers indicative a specific lymphoproliferative disorder) types can be seen, the latter perhaps related to splenic marginal zone lymphoma. The gene discussed is CD5; the disease is B-cell chronic lymphocytic leukemia.