Flow Cytometric DNA Index and Karyotype in Childhood Lymphoblastic Leukemia

Abstract

Flow cytometric DNA-index (DI^FCM) and karyotype were analysed in 82 consecutive children with acute lymphoblastic leukemia (ALL) during a 10 year period. A statistically significant correlation existed between modal chromosome number and DI^FCM (p = 0.009). DI^FCM could reliably identify leukemias with >51 chromosomes, whereas only three out of 12 cases with modal chromosome numbers between 47–51 were classified as aneuploid by DI^FCM. In the pseudodiploid group only one out of 20 leukemias had a DI^FCM>1.0. Five leukemias with a diploid karyotype showed an aneuploid DI^FCM and in three patients the flow cytometric measurement revealed biclonality undetected by karyotyping. During treatment aneuploid clones could be detected by DI^FCM in a substantial number of cases where the cytogenetic analysis was normal, and the opposite was also demonstrated in one case. DI^FCM gave prognostic information, showing that cases with a DI >1.12 (corresponding to 51 chromosomes) had a superior outcome with treatment protocols today in use.