Partial karyotypes of nine different cells from patient No. 26 showing centromeric heterochromatin decondensation of chromosomes 1, formation of triradial configurations, and movement of 1q. Cell showing normal 1s and der(19)t(1;19)(q10;p10) (arrow) (A). Chromosome 1 on right showing decondensation (arrow) (B). Both chromosomes 1 showing separations of short and long arms (arrows) (C). Somatic pairings of der (19)t(1;19)(q10;p10) and chromosomes 1 (arrows) (D through H). Subsequent instability of 19p10 and 1q10 (arrow) (I).