Abstract
As we know, the Philadelphia chromosome (Ph) is a highly specific marker for chronic myeloid leukemia (CML). This hematological disease is characterised by the formation of the BCR/ABL1 fusion gene, usually with typical translocation pattern including 9q34 and 22q11. In this paper we describe a 55 years old female patient with typical clinical and haematological signs of CML and a chromosome 9 differing from that which normally participates in translocation t(9;22). The karyotype of this Ph positive patient is characterised by pericentric inv(9)(p13q34) of the der(9)t(9;22)(q34;q11). Reverse transcriptase-polymerase chain reaction revealed a e14a2 type of BCR/ABL1 fusion transcript. As a consequence of this unusual translocation, FISH also found the separation of the ABL1/BCR1 fusion gene on chromosome 9. On reviewing the literature, to date only 10 Ph-positive leukemia patients have been noticed to have pericentric inversion inv(9)(p22q34)der(9)t(9;22)(q34;q11). No one case has been described with pericentric inversion inv(9)(p13q34) of the der(9)t(9;22)(q34;q11). This indicate that pericentric inv(9)(p13q34) of the der(9)t(9;22)(q34;q11) is a novel, rare, chromosomal abnormality in Ph-positive CML.
Highlights
It has long been known that chronic myeloid leukemia (CML) is a hyperproliferation of all circulating cell lines in the blood except lymphocytes
By rearranging the chromosome segments in the translocation t(9;22)(q34;q11), the BCR gene from chromosome 22 will be fused to the ABL1 gene derived from chromosome 9 resulting in the formation of the BCR-ABL1 fusion gene [2], [3]
In addition to the knowledge that ABL1 enzyme activity is a fundamental factor in the creation and maintenance of the neoplastic phenotype, little is known of the reciprocal chimeric ABL-BCR1 gene, formed at chromosome 9q [3]
Summary
It has long been known that chronic myeloid leukemia (CML) is a hyperproliferation of all circulating cell lines in the blood except lymphocytes. It is diagnosed by the presence of the BCR-ABL1 fusion gene, which is most often associated with the translocation t(9;22)(q34;q11). This chromosomal rearrangement leads to the well-known BCR-ABL1 fusion, formed by the combination of two normal ABL1 and BCR genes which encodes a 210-Kd (P210) fusion protein This protein has tyrosine kinase activity and cause inhibition of apoptosis resulting in excessive white blood cells production [1]. Despite the major breakthrough in the knowledge of the molecular events underlying the t(9;22) translocation, still no consistent data have been found on the correalation between those two chimeric genes, and what happens in case there is no ABL1-BCR fusion during and after chromosomes translocation process
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