Hikari Nishigaki

The unbalanced 1;7 translocation in de novo myelodysplastic syndrome and its clinical implication

In our chromosome study of 97 patients with myelodysplastic syndrome (MDS), six showed an unbalanced translocation between chromosomes 1 and 7 [−7, +der(1)t(1;7)(p11;p11)]. All of them had morphologic myelodysplasia in trilineage of bone marrow cells, and cytopenia was the major finding in the peripheral blood. All six patients had symptoms of infection at the time of diagnosis, and five showed immunologic abnormalities (polyclonal hypergammaglobulinemia in four and increased marrow plasma cells in three). None of the patients survived more than 11 months after the diagnosis; the median survival time was 4 months. Both of the two patients whose karyotypes were reexamined in the course of their disease showed karyotypic evolution accompanying the coincidental leukemic transformation. Six patients with MDS who had the same chromosome abnormality [t(1;7)] are described and their characteristic clinical features are presented.

Rejoining between 9q+ and Philadelphia chromosomes results in normal-looking chromosomes 9 and 22 in Ph1-negative chronic myelocytic leukemia

SummaryRearrangement of the breakpoint cluster region (bcr) and the chromosomal location of c-abl and 3′-bcr were studied in two patients with Philadelphia chromosome (Ph1)-negative chronic myelocytic leukemia (CML). One patient (patient 1) had a normal karyotype and the other (patient 2), 46,XY,inv(3)(q21q26). Both patients showed the bcr rearrangement by Southern blot analysis with a 1.2 kb 3′-bcr probe. In situ hybridization studies demonstrated the location of the homologous sequences of bcr on chromosome 22 in patient 1, and on chromosomes 9 and 22 in patient 2. These findings indicate that the morphologically normal-looking chromosomes 9 and 22 in patient 2 are the result of a retranslocation between chromosomes 9q+ and 22q-, abnormalities which were first formed by a standard Ph1 translocation.

Detection of karyotypic abnormalities in most patients with acute nonlymphocytic leukemia by adding ethidium bromide to short-term cultures

A modified short-term culture method, in which cultured bone marrow cells were treated with ethidium bromide to prevent chromosome condensation was used to study the chromosomes of 70 patients with acute nonlymphocytic leukemia. Clonal karyotypic abnormalities were detected in 60 patients. Among these, 35 patients showed one of recurrent type specific alterations. A close relationship between karyotypes and clinical outcome was shown: thus, t(8;21) or a single miscellaneous chromosomal defect associated with a favourable prognosis whereas t(9;11) or a complex karyotype related to a poor prognosis. The ten cytogenetically normal patients did not appear to have a favourable prognosis.

Reciprocal t(14;19)(q32.3;q13.1) in a patient with B-cell lymphoma

A patient with B-cell lymphoma with a chromosome rearrangement of t(14;19)(q32.3;q13.1) is reported. This patient had leukemic features and an aggressive clinical course. The histopathologic diagnosis was malignant lymphoma, small noncleaved cell. Chromosome analysis of the cells from a cervical lymph node and peripheral blood showed a reciprocal translocation between chromosome 14 with a break at band q32.3 and chromosome 19 with a break at band q13.1, to which the bcl-3 gene has been mapped. Monoclonal rearrangement of the JH gene was detected by Southern blot analysis. However, we could not detect rearrangement of the bcl-3 gene. This case also had a t(2;8)(q13;q24.1), but the c-myc gene remained in its germline. This is the first case with the reciprocal t(14;19) and 8q24 chromosomal breakpoint in a B-cell lymphoid malignancy.

Interphase Detection of t(4;14)(p16.3;q32.3) by In Situ Hybridization and FGFR3 Overexpression in Plasma Cell Malignancies

The immunoglobulin (Ig) genes are frequently involved in chromosomal rearrangements with a wide variety of partner loci in multiple myeloma (MM). However, several partner chromosomes have not been detected by conventional cytogenetic methods; for example, 4p16.3 (FGFR3), 6p25.3 (IRF4), and 16q23 (c-maf). To clarify the incidence of t(4;14)(p16.3;q32.3) in primary tumors of MM and to evaluate possible correlations with specific manifestations of the disease, G-banding, double-color fluorescence in situ hybridization (DC-FISH), and/or reverse-transcriptase polymerase chain reaction (RT-PCR) were performed on 40 patients with MM-two with plasmacytoma (PCM) and three with plasma cell leukemia (PCL). All patients were studied by DC-FISH; 40 were studied by G-banding and 36 were studied by RT-PCR. The FISH probes consisted of a cosmid pC385.12 containing the FGFR3 gene, a YAC Y6 containing VH, and a phage Iggamma1-10 containing the gamma1 constant region (Cgamma). We identified eight patients with either FGFR3/Cgamma fusion or FGFR3 overexpression: six patients with both FGFR3/Cgamma fusion and FGFR3 overexpression, one patient with FGFR3/Cgamma, and one with FGFR3 overexpression. FGFR3/Cgamma fusion was demonstrated at a frequency of 19% to 38% on interphase nuclei in seven of the 45 patients. Lytic bone lesions were found to be associated with FGFR3 overexpression. Interphase FISH with FGFR3 and Cgamma probes combined with RT-PCR proved to be an effective tool for detection of this fully cryptic translocation, thus facilitating the characterization of clinical features of MM patients with t(4;14).

Assignment of the human myeloperoxidase gene (MPO) to bands q21.3→q23 of chromosome 17

Using a human myeloperoxidase cDNA, we have mapped the human myeloperoxidase gene to chromosome 17 at q21.3----q23 by in situ hybridization to metaphase chromosomes from human lymphocyte preparations.

Myelodysplastic Syndrome Preceding Acute Myelomonocytic Leukemia with Dysplastic Marrow Eosinophilia and Inv(16)

A 44-year-old Japanese male having refractory anemia with excess of blasts (RAEB) preceding acute myelomonocytic leukemia (AMMoL) with dysplastic marrow eosinophilia (M4Eo in the FAB classification) is reported. Sequential cytogenetic studies revealed a specific chromosomal abnormality, inv(16) (p13q22), when RAEB was first diagnosed and again when overt leukemic transformation compatible with M4Eo was manifested. However, during the interval between the RAEB and AMMoL, an unrelated abnormal karyotype without inv(16), 47,XY,+9, was seen, when hematological data revealed remission after a low dose of cytosine arabinoside was administered. In this patient eosinophils in the marrow were involved in the leukemic process cytogenetically, because a few metaphases overlaid with eosinophilic granules had the inv(16) with other numerical abnormalities.

Translocation between chromosomes 8q24 and 14q11 in T-cell acute lymphoblastic leukemia.

Cytogenetic study was performed on a patient with T-cell acute lymphoblastic leukemia (T-ALL). It revealed a chromosomal translocation between chromosome bands 8q24 and 14q11. 8q24 is known to encode the oncogene c-myc, while 14q11 encodes the genes for T-cell receptor-alpha (TCR-alpha) and T-cell receptor-delta (TCR-delta). Therefore, this chromosomal translocation t(8;14) (q24;q11) seemed to be unique and specific to T-cell malignancy.

Simultaneous existence of double minute chromosomes and a homogeneously staining region in a retinoblastoma cell line (Y79) and amplification of N-myc at HSR☆

We observed double minute chromosomes (dmin) and a homogeneously staining region (HSR) in the same metaphase cells obtained from a retinoblastoma cell line, Y79. All of the 132 metaphases examined contained an HSR on the short arm of chromosome 1(1pHSR) and five cells (3.8%) had two to four dmin. To determine whether 1pHSR and dmin carried amplified N-myc sequences, we performed an in situ hybridization using an N-myc probe. Silver grains clustered on and along the 1pHSR, but not on the dmin. These findings indicate that the HSR on chromosome 1 is associated with amplification of N-myc in Y79 cells.

DNA analysis using long-term preserved fixed cytogenetic preparations

SummaryDNA was isolated from cell pellets that had been stored in methanol-acetic acid (3 : 1) at −20°C up to 6 years. These cell pellets contained high molecular weight DNA sufficient for Southern blot hybridization. The method enables us to study the DNA of a patient after completing chromosome analysis or in cases where DNA samples are otherwise not available.