The value of interphase fluorescence in situ hybridization for the detection of translocation t(12;21) in childhood acute lymphoblastic leukemia.
Translocation t(12;21)(p13;q22) is the most frequent cytogenetic abnormality in childhood acute lymphoblastic leukemia (ALL) and is generally associated with favorable prognosis. In this report, we assessed the value of dual-color interphase fluorescence in situ hybridization (FISH) for the detection of t(12;21). Fifty-three patients were screened for ETV6/CBFA2 fusion by means of FISH, using two cosmid probes mapped on ETV6 and on CBFA2, respectively. The cut-off value (mean + three standard deviations) for positivity established on control patients was 9.3%. A comparison between FISH and molecular methods [reverse-transcriptase polymerase chain reaction/Southern blot (RT-PCR/SB)] was possible in 52 patients: 34 of 52 (65.4%) showed negative results with both approaches, and 13 of 52 (25%) were positive; 5 of 52 (9.6%) showed discrepancies: four patients who were positive using RT-PCR/SB were negative using FISH. Conversely, one patient negative when using RT-PCR/SB was positive with FISH. Further investigations on this patients, cytogenetically characterized by add(12p), showed an atypical breakpoint on ETV6, located 5' to the common breakpoint. Compared with RT-PCR and SB, dual-color interphase FISH with the cosmid probe set proved to be highly specific but showed limited sensitivity.
Ameye
G
G
Center for Human Genetics UCL, Cliniques Universitaires St Luc UCL, Brussels, Belgium.
Jacquy
C
C
Zenebergh
A
A
Stul
M
M
Vaerman
J L
JL
Bilhou-Nabera
C
C
Libouton
J M
JM
Deneys
V
V
Martiat
P
P
Hagemeijer
A
A
Cornu
G
G
Verellen-Dumoulin
C
C
Michaux
L
L
D015139:Blotting, Southern; D002648:Child; D002675:Child, Preschool; D002881:Chromosomes, Human, Pair 12; D002891:Chromosomes, Human, Pair 21; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase; D007958:Leukocyte Count; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014178:Translocation, Genetic