We therefore sought evidence for analogous point mutations in the ABL gene in patients with Ph-negative, BCR-negative CML (n = 25), Ph-negative ALL (n = 18) and in Ph-positive CML in transformation (n = 28).
The first clear cut association of an oncogene with a specific cancer is the c-abl translocation in chronic myelogenous leukemia and acute lymphocytic leukemia; it has been observed in 90% of CML cases examined.
This case seems to represent an exceedingly rare instance of Ph1(+),i(17q) ALL in which the differential diagnosis between blast transformation of CML and Ph1(+) ALL was initially difficult to make.
Such rearrangements may be a feature of a small proportion of patients with non-lymphoid transformation of CML as they are in a minority of cases of de novo acute non-lymphoblastic leukaemia.
Rearrangements in the BCR gene first intron, the so-called bcr2 and bcr3 regions, were detected in two other cases, one with an acute lymphoblastic leukemia (ALL) and one with mixed acute leukemia.
In lymphoblastic leukemias, there are two molecular subtypes of the Ph1 chromosome, one with a rearrangement of the breakpoint cluster region (bcr) of the BCR gene, producing the same 8.5-kilobase BCR-ABL fusion mRNA seen in chronic myelogenous leukemia (CML), and the other, without a bcr rearrangement, producing a 7.0-kilobase BCR-ABL fusion mRNA that is seen only in acute lymphoblastic leukemia (ALL).
A series of five single-copy genomic probes from the 70-kilobase first intron of BCR were used to localize rearrangements in 8 of 10 Philadelphia chromosome-positive ALLs.
In some patients with Philadelphia (Ph)-chromosome positive acute lymphoblastic leukemias, breakpoints on chromosome 22 are reported to occur within the first BCR intron.
Molecular studies have demonstrated that the Philadelphia chromosome (Ph) translocation characteristic of chronic granulocytic leukemia (CGL) and 50% of the cases of Ph positive acute lymphocytic leukemia (ALL) involves a limited 5.8 Kb region on chromosome 22 termed the breakpoint cluster region (bcr).
Three cases of acute lymphocytic leukemia (ALL) and one case of chronic myelocytic leukemia in blastic crisis (CML-BC), which expressed only Tp40 antigen of cluster of differentiation (CD) 7 without erythrocyte rosette receptor (E), did not show rearrangements of TCR beta chain genes.
In CML the translocation breakpoint on chromosome 22 is within the breakpoint cluster region, while in childhood ALL, no detectable change in breakpoint cluster region is routinely observed.
Philadelphia (Ph1) chromosome breakpoints in acute lymphoblastic leukemia (ALL) are of two kinds: those within the breakpoint cluster region (bcr+), as in chronic myeloid leukemia (CML), and those outside it (bcr-).
Twenty patients had chronic myeloid leukemia in blast crisis (CML-BC), three had Ph+ de novo acute nonlymphocytic leukemia (ANLL), and five had de novo acute lymphoblastic leukemia (ALL).
A combination of monosomy 7 and translocation t(9;22) (q34;q11), rarely observed in acute lymphoblastic leukaemia (ALL), is here reported: a peculiarity of this case was that the "breakpoint cluster region" on chromosome 22 was not rearranged, as demonstrated by molecular analysis, and a new c-abl protein (p190) was found, instead of the usual p210 protein usually associated with the Ph chromosome; moreover a rearrangement of c-abl oncogene was found.
We report here observations on the occurrence of intermediate pre-B/B-cell phenotypes, immunoglobulin isotype switching and the asynchrony of immunoglobulin heavy and light chain expression in 30 cases of ALL and 3 cases of chronic myelogenous leukaemia in lymphoblastic crisis (CML-BC).
Homozygous deletions of p16 exons were found in 5 of 10 (50%) patients with CML in lymphoid BC and in 5 (26%) ALL patients, but in only 1 (2%) case with AML.
A patient with a typical haematological pattern of acute lymphoblastic leukaemia with BCR and IgH rearrangements was brought into complete remission by treatment.
95% of Chronic Myelocytic (CML) and 15-25% of Acute Lymphoblastic Leukemia (ALL) patients are Ph1 producing a fusion transcript between the abl proto-oncogene and the bcr gene.
Two-thirds of patients with Philadelphia (Ph) chromosome-positive acute lymphoblastic leukaemia (ALL) have a breakpoint in the minor breakpoint cluster region (m-bcr) of the BCR gene, which results in an e1a2 transcript and a P190BCR-ABL fusion protein.