FISH analysis confirms the presence of del(11)(p12p13) in T-ALL patient 1950. (A) Chromosome ideogram and overview of the genomic position of the BAC clones used for FISH analysis, located in the telomeric and centromeric breakpoint regions. (B) Dual-color FISH analysis on metaphase spreads of patient 1950 using RP11-465C16 (green), RP11-646J21 (green), and RP11-98C11 (red). The wild-type allele of chromosome 11 shows 2 green and 1 red signal, whereas on the mutated allele the red signal is lost and both green signals fuse. The extrachromosomal red signal represents background. (C) Dual-color FISH analysis on metaphase spreads of the same patient using RP11-465C16 (green) and RP11-603J2 (red). The intensity of the red signal is lower compared with the wild-type allele of chromosome 11, suggesting that only part of RP11-603J2 is deleted. (D) Dual-color FISH analysis on metaphase spreads using RP11-465C16 (green), RP11-646J21 (green), and RP11-36H11 (red). The wild-type allele of chromosome 11 shows 2 green and 1 red signal, whereas on the mutated allele the red signal is lost and both green signals fuse. (E) Dual-color FISH analysis on metaphase spreads using RP11-465C16 (green), RP11-646J21 (green), and RP11-769M16 (red). The wild-type allele of chromosome 11 shows 2 green and 1 red signal, whereas on the mutated allele the red signal is lost and both green signals fuse.