Detection of translocations affecting the BCL6 locus in B cell non-Hodgkin's lymphoma by interphase fluorescence in situ hybridization.
Structural alterations in 3q27 affecting the BCL6 locus are among the most frequent changes in B-NHL. The aim of the present study was to establish an interphase-FISH assay for the detection of all diverse BCL6 translocations in B-NHL. Two different approaches were tested, one using a PAC-clone spanning the major breakpoint region (MBR) of BCL6 (span-assay), and another using two BAC clones flanking the MBR (flank-assay). Interphase FISH with the span-assay detected the various BCL6 translocations in seven B-NHL cell lines. The dual-color flank-assay was evaluated in two laboratories independently: in normal controls, the cutoff level for false-positive signals was 2.6%, whereas the cutoff level for false-negatives in the seven cell lines was 7.5%. To test the feasibility of the FISH strategies, 30 samples from patients with B-NHL with cytogenetic abnormalities of 3q27 were evaluated with both assays. In 21 cases, the span-assay indicated a BCL6 rearrangement. In 18 of the 21 cases, the dual-color flank-assay confirmed the translocation including 12 different partner chromosomal loci. The three false-positive cases detected with the span-assay showed trisomy of chromosome 3 by cytogenetic analyses, and they were correctly classified as non-rearranged with the flank-assay. In summary, our FISH strategy using two differently labeled flanking BCL6 BAC probes provides a robust, sensitive, and reproducible method for the detection of common and uncommon abnormalities of BCL6 gene in interphase nuclei. The routine application of this assay to patients with B-NHL will allow the assessment of the diagnostic and prognostic significance of BCL6 rearrangements.
Sanchez-Izquierdo
D
D
Department of Hematology and Oncology, Hospital Clinico, University of Valencia, Spain.
Siebert
R
R
Harder
L
L
Marugan
I
I
Gozzetti
A
A
Price
H P
HP
Gesk
S
S
Hernandez-Rivas
J M
JM
Benet
I
I
Solé
F
F
Sonoki
T
T
Le Beau
M M
MM
Schlegelberger
B
B
Dyer
M J
MJ
Garcia-Conde
J
J
Martinez-Climent
J A
JA
D001483:Base Sequence; D002871:Chromosome Banding; D002893:Chromosomes, Human, Pair 3; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D016393:Lymphoma, B-Cell / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D014178:Translocation, Genetic