Aniridia + translocation, FISH & cosmid prob

Human chromosomes highlighted by fluorescent probes which bind to specific sequences of DNA. This FISH (fluorescence in situ hybridisation) study is of a patient with spoaraic isolated aniridia (failure of the iris to develop) and an apparently balanced translocation between chromosomes 7 and 11, t(7;11). These FISH results show that the break-point in 11p13 is between PAX6 (upper cell) which is retained on the der(11) - green centromere signals and red cosmids - and normal 11. The lower cell shows result with F02121 which lies about 100 KB distal to PAX6. In this case, the cosmid signals (in red as are the 7 and der(7)) can be seen on the normal 11 and der(7) respectively. The 11p13 break-point, therefore, lies in the approx 100 KB internal between PAX6 and