Patterns of FISH probes used in this study. (A) Schematic representation of the probe sets used for detection of the t(11;14)(q13;q32) breakpoint in chromosome 11q13, consisting of differentially labeled (green and red) pooled cosmids and P1-derived artificial chromosomes (PACs). (Adapted from Haralambieva et al¹⁶  with permission.) (B) Schematic representation of the immunoglobulin heavy chain (IgH) gene locus and the IgH FISH probes used in the CCND1 colocalization assay. Cosmid U2-2 covers JH and part of DH gene segments and cos3/64 covers the JH, Cδ, and Cμ gene segments, as described by Southern blotting analysis with segment-specific probes²²  and DNA fiber FISH mapping.²³  PAC clone PAC27M16 was mapped by DNA fiber FISH and located immediately 3′ of the immunoglobulin Ca2 region (J. Guikema, E.S., and P.M.K., unpublished results, May 2003). (C-F) Segregation FISH analysis. Panels C and D both show a t(11;14)(q13;q32) translocation indicated by the presence of segregated red and green signals. Panel E shows a monoallelic translocation break with loss of the derivative chromosome der11, as indicated by the presence of a single red signal and the lack of a green signal. The colocalized signal (red/green) represents the normal allele. (F) Segregation FISH analysis showing increased copy numbers for the CCND1 locus indicated by the presence of 3 colocalized signals. (G-I) Traditional interphase FISH analysis showing a trisomy (G), a polysomy (H), or a disomy (I). Original magnification × 630 for panels C-I.