Partial metaphases showing the normal and the rearranged chromosome 3. (a) Q-banding; (b) FISH cohybridization experiment, performed as previously described , using commercial PCP probes specific for 3p (Kreatech, prod. No. KBI-30104, green), and 3q (Kreatech, prod. No. KBI-30105, red); (c, d) FISH experiments with BAC (c) and fosmid (d) clones to define the breakpoint regions in chromosome bands 3p13 and 3q13.12; (e, f) FISH cohybridization experiments with probes defining the breakpoints in bands 3p12.2 (e) and 3q28 (f); (g) Schematic representation of the double inversion leading to the formation of the der(3) chromosome. I, II, III, and IV refer to contig maps of BAC and fosmid clones of the breakpoint regions in chromosome bands 3p13, 3q13.12, 3p12.2, and 3q28, respectively. The clones used in FISH are indicated by red rectangles; the red arrows point on the intervals (defined by the red vertical lines) containing the breakpoints.