FISH assays for the detection of t(6;14)(p21.1;q32.3).

(A-B) R-banding and FISH analysis of patient 5, Table 1. FISH was performed with chromosome 6p21 probes hybridizing immediately centromeric (green) and telomeric (red) of the CCND3 gene. Signals were observed on the intact chromosome 6 (colocalization of red and green signals) and on the der(14)t(6;14)(p21.1;q32.3) containing the telomeric 6p21 signal (red). The green signal (centromeric 6p21) was on a marker chromosome whose constitution could not be determined by morphology. (C-D, large picture) FISH with probes flanking the CCND3 locus in cases 2 and 4. An intact CCND3 locus is indicated by a colocalized red/green signal. The split indicates the break event. (D, small figure) FISH in case 6 shows a complexly aberrant nucleus with 2 intact CCND3 loci (fused signals) as well as a split of the signals, indicating the breakpoint in the CCND3locus. (E-G) FISH with probes spanning the IGH andCCND3 loci in cases 1 and 3, Table 1. As both IGH(green) and CCND3 (red) probe pools span the recurrent breakpoint regions 2 fusion signals (arrowheads) are to be expected, indicating the der(6)t(6;14)(p21.1;q32.3) and der(14)t(6;14)(p21.1;q32.3) in addition to each isolated signal indicating the intact IGH and CCND3 loci. This expected pattern is clearly seen in the aberrant metaphase (E) and the tumor cell nuclei (F) of case 3. In case 1 (G) the pattern is more complex, but fusion of IGH and CCND3 can be seen in most of the cells (arrowheads). On the basis of FISH analyses with differentially labeled probes flanking the CCND3 andIGH loci, respectively, the lack of one fusion signal and the supernumerary CCND3 signals detectable in many cells in this case is most likely due to a gain of one intact copy of the CCND3 locus and loss of the der(6)t(6;14)(p21.1;q32.3) (data not shown).