significance of cd66c expression in childhood acute lymphoblastic leukemia upon analyzing 696 childhood bcell precursor acute lymphoblastic leukemia bcpall cases we identified the characteristics of cd66c expression in addition to the confirmation of strong correlation with bcrabl positivity and hyperdiploid we further observed that cd66c is frequently expressed in crlf2positive 1115 p001 against chimeric genenegative as well as hypodiploid cases 34 whereas it is never expressed in etv6runx1 mllaf4 mllaf9 mllenl and e2apbx1positive cases although the expression of cd66c itself is not directly linked to the prognosis the accompanying genetic abnormalities are important prognostic factors for bcpall indicating the importance of cd66c expression in the initial diagnosis of bcpall