Chromosomal abnormalities in 2 patients with PNH. (A) Idiogram of normal chromosome 12 (Chr 12) modified from the NCBI Map viewer. Labeled gray boxes indicate the positions of the designated BAC clones used for FISH analysis. (B) J20. The karyotypic abnormality identified in the GPI-AP^– bone marrow cells of J20 was defined as an interchromosomal insertion. An 18.5M-bp region from q12 to q14 (surrounded by broken lines) is deleted in short chromosome 12 as defined by characterization of BP1. The 2.7-kbp small fragment (bracketed arrowhead, labeled a) and the 18.5-Mbp large fragment (bracketed rectangle, labeled b) deleted from short chromosome 12 are inserted inversely and directly, respectively, into the 12q14 region of long chromosome 12 generating BP2, BP3, and BP4. The deleted region into which the 2 fragments are inserted lacks 17 kbp of sequence (broken lines). BP1, BP2, BP3, and BP4 indicate the breakpoint junctions generated by the chromosomal abnormality. (C) US1. The karyotypic abnormality identified in the bone marrow cells of US1 was defined as an intrachromosomal insertion. The large fragment (19.5 Mbp, labeled c) and the small fragment (300 kbp, labeled d) are inserted into the TEL locus (gray arrowhead) on 12p13. BP5 is generated by the deleted region. BP6, BP7, and BP8 are generated by rearranged fragments c and d. (D) Sequences of BP junctions in J20 and US1. The sequences around BP junctions 1 to 8 are shown. BAC clones containing the sequence are denoted above the lines. Arrows indicate the nucleotide numbers of the BAC clones. Arrowheads indicate one of the candidate breakpoints, and gray regions indicate ambiguous sequences shared between the 2 BAC clones at the site of the breakpoint.