Human metaphase, translocation, cosmid probe

Human chromosomes at metaphase, highlighted with fluorescent probes that bind to specific sequences of DNA. This cell is from the amniotic fluid of a patient with an unbalanced translocation between chromosomes 4 and 9, t(4,9). The bcr cosmid (red) is present on both chromosome 9 homologues, and also at the distal tip of the short arm of the der(4) - chromosome 4. Image by Dr John Crolla.