Figure 2.

Mapping of chromosome breakpoints in patient 1. A, Metaphase chromosomes after FISH with BAC clones RP11-879D6 (green) and RP11-261A13 (red) showed that RP11-879D6 spans the breakpoint. B, DNA sequencing of both breakpoints of the derivative chromosomes 4 (green) and 17 (yellow) identified a 13-bp deletion on 4q28.3 generated by the translocation breakpoint. The breakpoint on chromosome 4 maps within a mariner transposon-like element HSMAR2. The trinucleotide CAC in bold represents the site of the translocation where there is identical sequence on both chromosomes 4 and 17 and may designate the origin of the translocation.