Partial karyotypes of nine different cells from patient No. 3 showing centromeric heterochromatin decondensation of chromosome 1 and association of 1q heterochromatin with 17q25. Duplications of 1q (open arrow) are found in addition to extra copies of translocated 1q (closed arrow) (A). Subtle decondensation of chromosomes 1 and crossing over of chromosomes 1 (B and C). Crossing over of der(17)t(1;17)(q10;q24) with chromosome 1 (arrows) (D and E). An extra free copy of 1q (G). Decondensation of chromosome 1 and der(17) (H). Chromosome 1q has jumped from der(17) to 7q leaving heterochromatin on 17q24 (arrow) (I).