FISH analysis of the 3 radiation-induced AML cases.

(A) Case 1. The 3 red signals represent the 2 AML1 genes on chromosome 21q22 and the translocation to chromosome 1p36. The green signal represents TEL on chromosome 12, which serves as an internal control for quality of the FISH. An arrow denotes the translocatedAML1 gene. A partial karyotype is below the FISH photomicrograph, showing the reciprocal translocation between chromosomes 1 and 21. (B) Case 2. The 3 red signals represent the 2AML1 alleles on 21q22 and the translocation to chromosome 18q21. Besides the 2 green TEL signals on chromosome 12, chromosome 18 was labeled with a centromeric probe. An arrow denotes the chromosome 18 with the AML1 translocation. A partial karyotype showing the chromosome 18 and 21 translocations is below the photomicrograph. (C) Case 3. The upper photomicrograph shows 3 green signals representing chromosome 21 paint, whereas the red represents chromosome 19 paint. There is extra chromosome 21q material on chromosome 19q13. An arrow denotes the AML1 translocation to chromosome 19. The lower photomicrograph shows the FISH analysis with the TEL-AML1 probe. The 3 red signals indicate the split AML1 gene. A partial karyotype showing the translocation between chromosomes 19 and 21 is also present.