ROR1 is expressed on hematogones (non-neoplastic human B-lymphocyte precursors) and a minority of precursor-B acute lymphoblastic leukemia

► Chronic lymphocytic leukemia (CLL) consistently expresses ROR1. ► Normal mature B cells do not express ROR1. ► This study shows that hematogones express surface ROR1 at an intermediate stage of maturation. ► Also, this study shows that less than 10% of B-ALL express surface ROR1. ► These ROR1+ B-ALL cases have an unusually high frequency of lacking CD34 and/or having t(1;19).