A case of mature B-cell ALL with coexistence of t(1;19) and t(14;18) and expression of the E2A/PBX1 fusion gene.
The translocation t(1;19)(q23;p13) is found in 3-5% of all acute lymphoblastic leukaemias (ALL) and results in the expression of an E2A/PBX1 hybrid gene transcript. This translocation is very closely associated with a pre-B phenotype. t(14;18) is associated with follicular B-cell lymphoma and is characterized by over-expression of the bcl-2 oncogene. We describe a case of ALL in an adult with a mature B-cell immunophenotype and a single abnormal cell line with a complex karyotype showing both t(1;19) and t(14;18). Two reports of this phenomenon have been published previously and molecular analysis, where performed, showed the E2A gene was not rearranged, suggesting the t(1;19) was a molecular variant of the established translocation. In contrast, molecular analysis of our case demonstrated expression of the E2A/PBX1 fusion transcript typically associated with t(1;19) in pre-B ALL but showed it to be present at an extremely low level, despite the abnormal karyotype being found in the majority of metaphase cells. Analysis of bcl-2 expression showed a significant up-regulation. A down-regulation of the E2A/PBX1 hybrid gene as a consequence of the enhanced expression of bcl-2 may be a possible mechanism for this finding.
Rowe
D
D
Department of Human Genetics, University of Newcastle upon Tyne.
Devaraj
P E
PE
Irving
J A
JA
Hogarth
L
L
Hall
A G
AG
Turner
G E
GE
D002051:Burkitt Lymphoma / Q000235:genetics*; D002878:Chromosomes, Human, Pair 1; D002883:Chromosomes, Human, Pair 14; D002887:Chromosomes, Human, Pair 18; D002888:Chromosomes, Human, Pair 19; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D016133:Polymerase Chain Reaction; D014178:Translocation, Genetic
D018398:Homeodomain Proteins; D015514:Oncogene Proteins, Fusion; C089847:E2A-Pbx1 fusion protein