FISH ANALYSIS OF TRANSLOCATIONS IN LYMPHOCYTES OF CHILDREN EXPOSED TOTHE 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 lymphocyt es of 20 Gomel (Belarus) children, including both thyroid tumor affect ed and healthy individuals. Gomel was one of the most heavily radio-co ntaminated areas due to fallout from the Chernobyl nuclear power plant disaster. As controls, 14 healthy children from Pisa (Italy) were inv estigated simultaneously. Translocation rates were significantly highe r 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 obs erved, in healthy Gomel children, an approximately threefold higher fr equency of chromosome 10 translocations compared to translocations aff ecting chromosomes 1 or 3 (P = 0.0096), a difference that was made eve n 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 radiat ion.