FISH analysis of translocations in lymphocytes of children exposed to the Chernobyl fallout: preferential involvement of chromosome 10.

Using whole-chromosome painting probes, we have analyzed the frequency of translocations of chromosomes 1, 3, and 10 in peripheral lymphocytes of 20 Gomel (Belarus) children, including both thyroid tumor affected and healthy individuals. Gomel was one of the most heavily radiocontaminated areas due to fallout from the Chernobyl nuclear power plant disaster. As controls, 14 healthy children from Pisa (Italy) were investigated simultaneously. Translocation rates were significantly higher in the tumor affected (1.71 +/- 0.68) and healthy Gomel children (2.69 +/- 0.50) than in the Italian controls (0.79 +/- 0.24). We also observed, in healthy Gomel children, an approximately three-fold higher frequency of chromosome 10 translocations compared to translocations affecting chromosomes 1 or 3 (P = 0.0096), a difference that was made even larger (about four fold) after correcting for chromosome size (P = 0.0009). This finding suggests a preferential involvement of chromosome 10 in translocations induced in vivo by low levels of ionizing radiation.