Molecular analysis of chromosomal breakpoints in three examples of chromosomal translocation involving the TEL gene

The TEL gene is involved in several chromosomal abnormalities of human hema topoietic malignancies. The chromosome 12 breakpoints frequently lie within the fifth intron of the gene, particularly in the most frequent translocat ion involving TEL, the t(12;21)(p13;q22). In order to search for a peculiar mechanism involved in the genesis of these translocations, we have establi shed the sequence of two t(12;21) and a t(9;12)(q24;p13) breakpoints. Our d ata do not reveal the involvement of VDJ recombinase activity or Alu sequen ces but favor the occurrence of staggered breaks and DNA repair activity in the genesis of these translocations.