Figure 1

Karyotypes from Case nos. 1–4 (A - D, respectively) showing unbalanced 1q arm translocations. Serial tetraploidisation is shown on the right hand karyotype. A) Reciprocal translocation t(1;9) with two additional copies of the derivative (1q)t(1;9) with subsequent rearrangement on 6p prior to tetraploidisation. B) Two unbalanced translocations showing translocation of 1q with the der(18)t(1;18) and der(20)t(1;20) as well as an interstitial deletion on 13q. C) The der(6)t(1;6) resulting in gain of 1q material and loss of distal 6p as the sole karyotypic abnormality (loss of chromosome 20 was random). D) Complex karyotype showing the additional derivative (1q) from the der(1;7)(q10;p10) resulting in gain of both 1q and 7p. Gain of 8, pericentric inversion 12 and deletion 22q are also evident. The tetraploid karyotype shows acquisition of the t(6;9)(p22;q34).