Figure 4. .

Topography of FANCD2, its pseudogenes, and the superamplicons. A, The two pseudogenes—FANCD2-P1 and FANCD2-P2—located upstream and downstream, respectively, of the functional FANCD2 gene. All three have the same orientation. The scale denotes Mb on chromosome 3. B, FANCD2 exons and their pseudogene equivalents, connected by dashed lines, indicating percentages of nucleotide identity. Homology also extends into many introns nearby, as indicated by the boxes beyond and below the active gene. C, Graphic presentation of the positions and sizes of 7 superamplicons relative to the active gene shown in panel B. These amplicons represent FANCD2 exon-exon or exon-intron regions. Unique primer-binding sites ensure specific amplification.