Prader Willi & Angelman syndromes - FISH

Human chromosomes highlighted by fluorescent probes that bind to specific sequences of DNA. This FISH (fluorescence in situ hybridisation) study uses a probe (red) from the Prader Willi and Angelman's syndromes critical regions (PWASCR) and a chromosome 15 centromere specific probe (green) to diagnose an interstitial duplication of proximal 15q11->q13 which includes the PWASCR. The cell on the left is not duplicated, whereas the cell on the right (960883) shows 3 copies of SNRPN in the abnormal chromosome 15. Also note that this cell shows 4 green signals, two of which came from an inverted duplicated marker (15) chromosome also found in all this patient's cells. Image by Dr John Crolla.