The gene fusion leads to changes in transcription and gene products

The ABL gene codes formRNA transcripts of 7 kb
(exon 1b, 2–11) and 6 kb (exon 1a, 2–11) by
differential splicing; these in turn code for a
protein of about 145000 Da (p145abl). From the
fusion of the two genes in CML, an 8.5 kb mRNA
transcript results, which codes for a fusion protein
of 210000 Da (p210bcr/abl). In the acute form
of leukemia (ALL), a transcript results that codes
for a fusion protein of 190000 Da (p190bcr/abl). In
contrast to the normal protein, it has high tyrosinase
activity. This results in uncontrolled
cell division in the affected cells and tumor
growth.