Progression of sequential JT1q12s in patients 15 and 32 demonstrating “passenger” segments on the JT1q12. (A) In patient 15, an isochromosome 1q (left bracket) is shown with FISH probes 1q12 (red) and 1q21 (green) on the left, SKY in the middle, and MLL (11q23) (yellow) on the right. The middle bracket shows a JT1q12 has translocated to the distal end of the long arm of 18, with the 11q23 (MLL) as a passenger. Note: der(18) on the right is probed for BCL2 (red). The bracket on the right shows the second jump of the same JT1q12 to chromosome 21p. As a result of this translocation, SKY identified an extra copy of both BCL2 and MLL duplicated and translocated to 21p. The resulting CNAs in this cell line were 3 copies of 1q21, 3 copies of BCL2, and 5 copies of MLL. (B) Patient 32 demonstrated JT1q12 translocations to 3 different RCs. A 3-chromosome segment involving 1p36, 1q12∼23, and 4p16 (FGFR3) translocated to the der(12) (left bracket). Two additional copies of JT1q12 with this 3-chromosome segment (1p36 proximally, 1q12∼23, and 4p [FGFR3] distally) translocated to both 8p (middle bracket) and 15p (right bracket).