Tissue-specific relative chromosome positioning correlates with tissue specific translocation frequency. (a) FISH analysis of chromosome 5 (green), 6 (red), 12 (green) and 15 (red) in hepatocytes or lymphocytes. Arrowheads indicate proximal pairs. Scale bar, 2 μm. Pairs of chromosomes 5-6 are more frequent than pairs of chromosomes 12-15 in hepatocytes, whereas the opposite is true in lymphocytes. (b) Determination of the percentage of hepatocytes or lymphocytes containing at least one 5-6 or 12-15 pair. The likelihood of pair formation correlates with the observed tissue-specific translocation frequency among these chromosomes. Dotted lines represent expected values based on a uniform random distribution. Note that the expectation value of contingency tables is dependent on the number of analyzed cells. For analysis of 5-6 pairing, 83 hepatocytes and 118 lymphocytes were analyzed. For analysis of 12-15 pairing, 158 hepatocytes and 88 lymphocytes were analyzed.