title: Direct visualization of dispersed 11q13 chromosomal translocations in mantle cell lymphoma by multicolor DNA fiber fluorescence in situ hybridization.
abstract: Several hematologic malignancies are associated with specific chromosomal translocations. Because of the dispersed distribution, chromosomal breakpoints may be difficult to detect using molecular techniques. We present a new application of a recently developed method, DNA fiber fluorescence in situ hybridization (fiber FISH), which allows direct visualization and mapping of chromosomal breakpoints. We tested this method for detection of the t(11;14)(q13;q32) translocation in mantle cell lymphoma. In DNA fiber FISH, a series of fluorochrome-labeled DNA probes covering several hundreds of kilobasepairs is hybridized to linear DNA molecules (or fibers) prepared from frozen tissue or intact cells. By using alternate fluorescent colors, a potential breakpoint region is stained in a color barcode pattern. Breaks in this region will split the barcode in two complementary parts, from which the breakpoint position can be derived. We used a 250-kb barcode covering the BCL-1 locus to detect 11q13 breakpoints in 20 well-characterized mantle cell lymphomas. A t(11;14) was shown by cohybridization of these probes with probes for the Ig heavy chain locus at 14q32. In 18 of 20 mantle cell lymphomas, a breakpoint within the 11q13/BCL-1 barcode was shown by the presence of multiple, complementary translocation products. Fusion of 11q13 and 14q32 sequences on single fibers indicating t(11;14)(q13;q32) was found in all 18 breakpoint-positive mantle cell lymphomas. In one additional case, fusion of an intact 11q13 barcode with 14q32 sequences indicated a breakpoint 100 kb centromeric of the major translocation cluster of BCL-1. Within the 120-kb region of BCL-1, breakpoints were widely scattered. This explains why, so far, a BCL-1 breakpoint had been detected by Southern blot analysis in only 10 of 19 cases. DNA fiber FISH analysis showed a t(11;14) in 95% of mantle cell lymphoma. The results indicate that DNA fiber FISH is a rapid, simple, and equally powerful method for detection of clustered and dispersed translocation breakpoints.
authors.affiliation: Department of Pathology, Leiden University Hospital, Leiden University, The Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Vaandrager
authors.forename: E
authors.initials: E
authors.lastname: Schuuring
authors.forename: E
authors.initials: E
authors.lastname: Zwikstra
authors.forename: C J
authors.initials: CJ
authors.lastname: de Boer
authors.forename: K K
authors.initials: KK
authors.lastname: Kleiverda
authors.forename: J H
authors.initials: JH
authors.lastname: van Krieken
authors.forename: H C
authors.initials: HC
authors.lastname: Kluin-Nelemans
authors.forename: G J
authors.initials: GJ
authors.lastname: van Ommen
authors.forename: A K
authors.initials: AK
authors.lastname: Raap
authors.forename: P M
authors.initials: PM
authors.lastname: Kluin
mesh_terms: D002869:Chromosome Aberrations / Q000175:diagnosis*; D025063:Chromosome Disorders; D002874:Chromosome Mapping / Q000379:methods; D002880:Chromosomes, Human, Pair 11; D003360:Cosmids; D019938:Cyclin D1; D016213:Cyclins / Q000235:genetics; D004273:DNA, Neoplasm / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping / Q000379:methods; D008228:Lymphoma, Non-Hodgkin / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics; D014178:Translocation, Genetic
chemical_list: D016213:Cyclins; D004273:DNA, Neoplasm; D015513:Oncogene Proteins; D019938:Cyclin D1