Genomic aberrations are frequently detected by FISH in CLL-like MBL clones. FISH analysis has been performed on CD5⁺CD20^dim purified MBL cells and shows, (A) on the left, a normal nucleus with 2 signals for each probe (Spectrum Aqua, Orange, and Green) corresponding to LSI13q34 locus 13q34, LSI D13S319 locus 13q14.3, and CEP 12 locus 12p11.1-q11, respectively; on the right another nucleus with a heterozygous deletion of the LSI D13S319 locus 13q14.3 (1 Spectrum Orange signal and 2 normal Spectrum Aqua and 2 Spectrum Green signals). (B) Both nuclei show trisomy of CEP 12 locus 12p11.1-q11 (3 Spectrum Green signals) and 2 normal Spectrum Orange signals (LSI D13S319 locus 13q14.3). (C) Both nuclei show the presence of only one signal for LSI p53 locus 17p13.1 (Spectrum Orange) and a normal double signal for LSI ATM locus 11q22.3 (Spectrum Green). Microscope used for these images was Nikon Eclipse 90i with a magnification ×1000 (Objective PLAN APO VC 100X/1:40 oil; 10× ocular; room temperature), and camera used was Qicam Fast 1394 (Qimaging). The imaging medium used was DAPI (Vectashield Mounting Medium with DAPI, vector). Acquisition software was Genikon (Nikon Instruments S.P.A.) and a FISH 3D Acquisition Module was used.