It is well-known that development of overt leukemia in t(12;21)-positive ALL requires secondary chromosomal aberrations although the full spectrum of these cytogenetic alterations is yet unsettled, and also, how they may be associated with disease outcome.
Further, the study adds to understanding the full spectrum of secondary chromosomal aberrations in the very common t(12;21)-positive pediatric ALL disease group.
The chromosomal translocation t(12;21) resulting in the ETV6/RUNX1 fusion gene is the most frequent structural cytogenetic abnormality among patients with childhood acute lymphoblastic leukaemia (ALL).
Karyotyping of more tongue SCC cases will expand the knowledge regarding chromosomal aberrations in SCC and thus might shed light on the significance of t(12;14) shown in this study.
We hope that our discovery of a new translocation t(12:21)(q13q22) will encourage further investigation into the molecular basis of this translocation and other cytogenetic abnormalities in primary cutaneous B-cell lymphomas.
The t (12;21) was the commonest chromosomal anomaly detected in this population; 14 out of the 45 pediatric patients (31%) were positive for TEL/AML1 fusion, among which three had an additional derivative 21 [t (12;21)], four had a deletion of 12p and two had an extra copy of chromosome 21.
Eight of 12 cases positive for t(12;21), and with conventional cytogenetic data, had structural and/or numerical chromosome abnormalities other than the detected t(12;21).
To determine whether specific cytogenetic abnormalities accompany the t(12;21), we analyzed the cytogenetic profiles of blast cells from 169 ALL cases positive for the t(12;21), previously identified by molecular methods.
The t(12;21) is a recurring chromosomal abnormality in acute lymphoblastic leukaemias (ALLs) which results in the production of an ETV6-AML1 fusion gene.
Translocation t(X;18) was detected in 25/28 synovial sarcomas; translocation t(11;22) in 5/6 Ewing's sarcomas and primitive neuroectodermal tumors (PNET); and translocation t(12;16) was found in 12/13 liposarcomas, including 10 myxoid and two round cell types as clonal chromosomal aberrations specific for both subtypes.
A BCR/ABL-negative chronic myeloid leukemia (CML) with t(12;14) (p12;q11-13) as the sole chromosomal abnormality was investigated by fluorescence in situ hybridization (FISH), which disclosed a cryptic insertion of ETV6 (previously called TEL), located at 12p12, into ABL at chromosome band 9q34.
A direct association between t(12;19) and these hematologic findings will have to be established as more cases with this chromosomal abnormality are identified.