The Philadelphia chromosome (Ph), produced by the reciprocal t(9;22)(q34;q11.2), is the cytogenetic hallmark of chronic myeloid leukemia (CML) and is observed in more than 90% of CML cases. At diagnosis, 5–10% of CML patients show variant translocations with the involvement of at least a third chromosome, in addition to chromosomes 9 and 22. In the majority of variant t(9;22) translocations, the Ph chromosome is cytogenetically detectable whereas the der(9) is rearranged with a different partner chromosome. The most frequent location of the BCR/ABL fusion gene in complex chromosomal rearrangements is 22q11.2, but in rare variant cases, BCR/ABL is translocated or inserted at sites other than 22q11.2; in fact, in several cases, the BCR/ABL fusion gene is located at 9q34. Moreover, in rare cases, the Ph is masked in the form of additional material transposed on the derivative chromosome 22. The mechanism of these rearrangements is difficult to determine as serial translocations or a single simultaneous event could be alternatively hypothesized . In the present report, we describe a Ph+ CML case showing an insertion into the long arm of the chromosome 9 of a region belonging to the der(9)t(9;22) and located centromerically to ABL; this chromosomal rearrangement was detected in concomitance with the presence of the 5'BCR/3'ABL fusion gene on the Ph chromosome.
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|Titolo:||The double deceit generated by an insertion mechanism in chronic myeloid leukemia with t(9;9;22)|
|Data di pubblicazione:||2008|
|Appare nelle tipologie:||1.1 Articolo in rivista|