ABSTRACT
Neurofibromatosis type 2 (NF2) is a brain tumor predisposing syndrome caused by inactivating alterations of the NF2 gene mapped at chromosome 22q. Currently, no genetic information exists on medulloblastomas occurring in NF2 patients. We herein report on the genetic alterations observed in a girl in which the NF2 gene was de novo altered due to a constitutional translocation: t(5;22)(q35.1;q11.2). This girl had a particularly aggressive disease course. At the age of 4, she had already been diagnosed with three lesions classified as schwannomas and a meningioma. At 10 years old, she developed a medulloblastoma. She died at the age of 14 due to a refractory acute myeloid leukemia (AML). From the genetic point of view, we observed that (1) the NF2 gene was rearranged in all patient samples: blood, tumor, and leukemic cells; (2) loss of 3' region of NF2 and the downstream regions of chromosome 22 were only detected in medulloblastoma cells; (3) the known cancer AML-related gene: NPM1 which is mapped at 5q35.1 was not the target of any alteration in our patient. Our data suggest that inactivation of the NF2 gene was relevant for the medulloblastoma pathogenesis. Furthermore, we know that malignant cancers are the result of a multi-epi-genetic sequence of events, and although, unquestionably limited to the genetic findings in one case. We may hypothesize, that as described for a fraction of medulloblastomas, the alteration of a gene mapped at 5q might also have been relevant for medulloblastoma development in our patient.
ABSTRACT
Hypereosinophilia, either clonal or reactive, has been described in association with multiple hematological malignancies. We describe a case of a patient presenting with hypereosinophilia that evolved into T-cell lymphoblastic lymphoma. Complete remission was achieved with chemotherapy; however, hypereosinophilia recurred 5 months later in association with myeloblastic bone marrow infiltration and without evidence of lymphoblastic lymphoma relapse. Cytogenetic analysis of the bone marrow showed a complex translocation involving chromosomes 7, 12, and 16. A rearrangement of ETV6 gene (12p13) was demonstrated by FISH studies, thus confirming the clonality of this population. The association of lymphoblastic lymphoma, eosinophilia, and myeloid hyperplasia has been described in disorders with FGFR1 rearrangements. We hypothesize that other clonal eosinophilic disorders lacking this rearrangement could behave in a similar fashion through different pathogenic mechanisms.
ABSTRACT
The MLL gene, at 11q23, undergoes chromosomal translocation with a large number of partner genes in both acute lymphoblastic and acute myeloid leukemia (AML). We report a novel t(9;11;19)(p22;q23;p13.3) disrupting MLL in an infant AML patient. The 5' end of MLL fused to chromosome 9 sequences on the der(11), whereas the 3' end was translocated to chromosome 19. We developed long-distance inverse-polymerase chain reaction assays to investigate the localization of the breakpoints on der(11) and der(19). We found that intron 5 of MLL was fused to intron 5 of MLLT3 at the der(11) genomic breakpoint, resulting in a novel in-frame MLL exon 5-MLLT3 exon 6 fusion transcript. On the der(19), a novel gene annotated as FLJ10374 was disrupted by the breakpoint. Using reverse transcription-polymerase chain reaction analysis, we showed that FLJ10374 is ubiquitously expressed in human cells. Transfection of the FLJ10374 protein in different cell lines revealed that it localized exclusively to the nucleus. In serum-starved NIH-3T3 cells, the expression of FLJ10374 decreased the rate of the G1-to-S transition of the cell cycle, whereas the suppression of FLJ10374 through short interfering RNA increased cell proliferation. These results indicate that FLJ10374 negatively regulates cell cycle progression and proliferation. Thus, a single chromosomal rearrangement resulting in formation of the MLL-MLLT3 fusion gene and haplo-insufficiency of FLJ10374 may have cooperated to promote leukemogenesis in AML with t(9;11;19).
