Fig. 2

Pericentromeric array CGH plots and fluorescence in situ hybridization (FISH) images for small supernumerary marker chromosomes (sSMCs) derived from chromosome 22. Array CGH data for the 22q pericentromeric region clones represented on the microarray are displayed with the most proximal clone on the left and the most distal clone on the right. The blue line is a plot of the data from the first array CGH experiment from the top half of the slide (reference Cy5/patient Cy3). The pink line is a plot of the data from the second array CGH experiment from the bottom half of the same slide in which the dyes have been reversed (patient Cy5/reference Cy3). A. A normal array CGH plot for the chromosome 22q pericentromeric region. B. Case 13 showing a gain of all clones across approximately 7.57 Mb of 22q pericentromeric DNA (22q11.1-q11.23) including the cat eye and DiGeorge syndrome critical regions. The log₂ ratio for all clones is just under 0.3 (rather than approximately 0.6) because the marker is found in only 57% of cells. C. Case 15 (the plots for cases 12 and 14 were essentially identical) showing a gain of approximately 2.2 Mb across the proximal pericentromeric region (22q11.1-q11.21) including the cat eye syndrome critical region but not the DiGeorge syndrome critical region, which is located approximately 3.7 Mb from the centromere. The log₂ ratio for the six most proximal clones is just over 0.6 indicative of tetrasomy for the region. This marker 22q was found in 100% of cells examined in this patient. D. FISH image of an sSMC 22q in case 13 (arrow). Clone RP11-1037C4 (cat eye region clone) is labeled in red with a 22q telomere clone (RP11-676E13) labeled in green as a control. The two red signals on the marker suggest that the marker contains two copies of the cat eye region. This is consistent with tetrasomy 22q in this patient. FISH using the same RP11-1037C4 probe labeled in red and the Cytocell 14/22 centromere probe labeled in green identified only one green centromeric signal on the marker (inset) consistent with a monocentric marker 22q. E. FISH image of an sSMC 22q identified in case 15 (arrow). Clone RP11-1037C4 (cat eye region clone) is labeled in red with a 22q telomere clone (RP11-676E13) labeled in green as a control. FISH using the Cytocell 14/22 centromere probe as described in E identified a dicentric marker 22q (inset).