In classical t(9;22) translocation, as observed in chronic granulocytic leukemia (CGL), a hybrid DNA unit is produced, including a rearranged PHL gene, previously known as
bcr (breakpoint cluster region) plus the translocated
c-abl gene from chromosome 9: a hybrid
bcr-abl protein, p210 is formed, with increased tyrosine kinase activity. Such DNA rearrangement, with a p210 protein synthesis, is also found in cases of Philadelphia-positive acute lymphoblastic leukemia (ALL), but in apparently similar cases the
bcr gene is not rearranged, and a novel p190
abl-related protein can be found;
c-abl rearrangement has also been observed.
It is thus established that correlations between cytogenetic and molecular events can be found in CGL and ALL, as in other haemopoietic malignancies: translocation and possible rearrangement of the c-abl oncogene seem of particular importance in this case.
Key words acute lymphoblastic leukemia - Philadelphia chromosome abl proto - oncogene p190 abl protein