Molecular studies revealed this involved the c-ABL gene on chromosome 9 and the BCR gene on chromosome 22, producing a fusion gene on the
derivative chromosome 22 of the 5' region of BCR with the 3' region of the c-ABL gene.
The translocation leads to fusion of the proto-oncogene Abelson (ABL) and a particular DNA sequence known as breakpoint cluster region (BCR), thereby giving rise to 2 new chimeric genes 5' ABL-3' BCR on the
derivative chromosome 9 and 5' BCR-3' ABL on the
derivative chromosome 22.
In 2008, Wettach et al (23) described a clonal reciprocal translocation between chromosomes 1 and 10 in one HFLT, along with a further rearrangement involving the
derivative chromosome 1 and chromosome 3.
In the present study 1 patient had a
derivative chromosome 7 (patient No.
Interestingly, fluorescence in situ hybridization (FISH) with an MLL break-apart probe set, performed on both interphase nuclei and metaphase spreads, confirmed the presence of 3 extra copies of the MLL gene on the
derivative chromosome 11.