Gene rearrangements and transcription evidence of PRDM7. (A) Effects of the internal duplication of ancestral exon 3 on PRDM7 splicing. The entire sequence of the ancestral exon 3 is reported; shown are the 89-long segment that undergoes duplication (bold) and the putative cryptic splice sites (red). The duplicon is represented as underlined text. After duplication, the non-canonical splice site (GC-AG) can be activated leading to intron splicing. The entire region can also be retained into the transcript resulting in a protein with no Zn-Fingers due to the introduction of a frameshift. The region in between the two red arrows was amplified in a variety of normal and tumoral samples, as reported in the panels (B). (B) RT-PCR analysis of exon 3 in normal tissues and cancer cell lines. The upper panel reports amplifications in normal samples, while the lower in cancer cell lines. We verified by sequence analysis that the upper band corresponds to PRDM7 exon 3 retaining the duplicated segment. The lower band can be either exon 3 of PRDM9 or exons 3-4 of PRDM7, since the two genes are indistinguishable in this region.