Figure 1.
Bar code representation and results of probe studies. (A) This figure is a schematic representation of the bar code obtained with the combination of all the probes. Because of the evolutionary duplication of the γ, ϵ, and α regions, all the probes specific for these regions generated 2 stretches. Also, because of the conservation of the γ loci, the γ4 probe hybridized to all these γ loci. Finally, the Ig10 probe generated 4 signals (instead of 2), 2 signals corresponding to the ϵ and α loci, and 2 other smaller signals, located on the telomeric side of the normal hybridized region. Of note, one of the smaller γ signals is located on the 3′ side of ψγ, enabling us to differentiate this ψγ signal from an extra γ signal (polymorphism). The yellow signals correspond to the superimposition of green and red signals. (B) The first image represents a nonrearranged IgH allele from the HL60 leukemia cell line, hybridized with the U2-2, 3/64, Ig6, and γ4 probes. The second image represents the same allele hybridized with the Ig6, Ig10, and α2 probes. (C) This fiber presents a legitimate switch (μ-γ1, patient 16). The U2-2 probe is not visible because of the large size of the deleted regions. The 3/64 probe generates only a small green signal on the 5′ side of γ1. This patient presents an extra γ signal within the centromeric γ stretch (polymorphism). (D) A nonrearranged fiber observed in patient no. 6, hybridized with the U2-2, 3/64, Ig6, and γ4 probes. (E) This fiber, hybridized with the U2-2, 3/64, Ig6, and γ4 probes, is also in germline configuration (patient no. 8). Of note, this fiber presents an extra signal with the γ4 probe, corresponding to a polymorphism. (F) This fiber (from the SKMM1 HMCL) has been hybridized with the U2-2, 3/64, Ig6, and γ4 probes and shows a nonfunctional rearrangement with deletion of the DNA located between the 3/64 and ψγ regions. (G) A typical fiber from patient no. 1, presenting a t(11;14), and hybridized with the Ig6, γ4, and 799B16 (specific for 11q13) probes. This fiber clearly shows a CCND1-IgH rearrangement involving the Sγ2 region. (H) This fiber (from the OPM2 HMCL) has been hybridized with the Ig6, Ig10, γ4, and FGFR3 probes, showing a typical FGFR3-IgH rearrangement involving the Sγ2 region.