Reassessment of childhood B-Lineage lymphoblastic leukemia karyotypes using spectral analysis

We studied a stratified cohort of 51 childhood B-lineage acute lymphoblasti c leukemias (B-ALLs) to evaluate the efficiency of spectral karyotyping (SK Y) in the detection of chromosome aberrations previously diagnosed using ch romosome banding and/or reverse transcriptase polymerase chain reaction. De spite the small number of cases analyzed, several important features emerge from the study: (a) The result of banding analysis was revised in two-thir ds of the cases. Eighty-three chromosome anomalies previously undetected or not characterized using chromosome banding were identified by spectral kar yotyping, even in patients with apparently normal karyotypes. (b) All hyper diploidy cases showed one or more extra copies of chromosomes X, 14, and 21 . (c) Two hidden rearrangements, a t(7;12)(?p 12;p13), and a new translocat ion, a t(9;12)(q31; p13), both involving the TEL gene, were characterized. (d) Some cryptic rearrangements, such as the der(21) t(12;21) translocation , remained undetected. (e) No new recurrent chromosome anomalies were disco vered with this technique. In conclusion, the present study confirms the ef ficiency of the SKY technique in resolving and characterizing many complex chromosome anomalies seen in childhood B-ALLs, but it raises questions abou t the ability of this technique to detect cryptic rearrangements, such as t he t(12;21) translocation. (C) 2001 Wiley-Liss. Inc.