The majority of myeloid-antigen-positive (My+) childhood B-cell precursor acute lymphoblastic leukaemias express TEL-AML1 fusion transcripts.
The t(12:21) translocation fuses the TEL and AML1 genes and has been found in up to 28% of paediatric B-cell precursor acute lymphoblastic leukaemias (BCP-ALL). The AML1 gene is a transcription factor which regulates expression of several myeloid differentiation associated genes. A molecular analysis of TEL-AML1, E2A-PBX1, MLL-AF4, BCR-ABL expression and an immunophenotypic study of CD13/CD33 myeloid antigen expression have been performed prospectively on tumour cells from 96 paediatric BCP-ALL patients. Percentages of CD13 or CD33 expressing leukaemic cells were found to be higher in TEL-AML1 positive cases (n = 22) than in TEL-AML1 negative (n = 74) cases (P<0.001). In 22/96 cases (23%) >10% of neoplastic cells were found to express at least one of the two markers. In 14 of these cases (63%), TEL-AML1 expression was detected, whereas t(4;11), t(11;19) and t(9;22) translocations were found by molecular methods in only three cases (14%). In four cases (18%) no molecular marker was found. These data show that TEL-AML1 expression is significantly associated with myeloid antigen expression by leukaemic cells and suggests that the prognostic significance of myeloid antigen expression in paediatric ALLs should be re-evaluated in the light of molecular cytogenetic markers.
Baruchel
A
A
Molecular Haematology Laboratory and INSERM Unit U432, Hôpital Saint Louis, Paris, France.
Cayuela
J M
JM
Ballerini
P
P
Landman-Parker
J
J
Cezard
V
V
Firat
H
H
Haddad
E
E
Auclerc
M F
MF
Valensi
F
F
Cayre
Y E
YE
Macintyre
E A
EA
Sigaux
F
F
D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism*; D015139:Blotting, Southern; D002648:Child; D002675:Child, Preschool; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism; D006801:Humans; D016130:Immunophenotyping; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014178:Translocation, Genetic / Q000235:genetics
D015214:Antigens, Differentiation, Myelomonocytic; D015514:Oncogene Proteins, Fusion; D014157:Transcription Factors; D016044:Fusion Proteins, bcr-abl