Translocation shown up by cosmid probe

Human chromosomes at metaphase, highlighted by fluorescent probes that bind to specific sequences of DNA. This shows the use of such probes in prenatal diagnosis of an unbalanced form of a translocation between chromosomes 4 and 16 (t(4;16). The RT1 cosmid (red) which maps to 16o13.3 can be seen at the end of both short arms of chromosome 16, and also at the tip of the short arm of the der (14) (chromosome 14), thus confirming that the foetus is unbalanced. The 4 and 16 centromeres are labelled in green, and there is some cross-hybridisation to the centromeres of chromosomes 1 and 5. Image by Dr John Crolla.