Figure 2

a) Molecular cytogenetics revealed in case B (= case 16 in Tab. 1) t hat the sSMC was derived from chromosome 13 or 21, as the centromeric probe (D13/21Z1 – green) and a probe specific for all acrocentric p-arms (midi54 – blue) were present on the marker. However, no centromere-near material, neither from chromosome 13 nor 21 was detectable on the marker (pink and red probes). b) Three-color-FISH using partial chromosome painting (pcp) probe for the short (green) and the long arm of chromosome 18 (blue) together with a probe for the centromere-near region of 18p11.2 (red) revealed that the whole short arm was present on the sSMC.