Specific chromosome markers involved with chronic T lymphocyte tumors

Inversions of chromosomes 2 and 6 in mantle cell lymphoma. Cytogenetic, FISH, and molecular studies

Inversions are infrequent events in hematological malignancies. We here report the cytogenetic, fluorescence in situ hybridization (FISH), and molecular studies of 2 patients diagnosed with mantle cell lymphoma (MCL) that showed inversions of chromosomes 2 and 6 as part of complex karyotypes. Both patients showed a cytogenetically identical inv(6)(p23q11) detected as a secondary aberration. In addition, both patients had a derivative chromosome 2 which originated by partial deletion of the short arm and a pericentric inversion with different breakpoints on the long arm: der(2)del(2)(p21)inv(2)(p21q11) and der(2)del(2)(p21)inv(2)(p21q13), respectively. The presence of t(11;14)(q13;q32) was confirmed by interphase FISH and by molecular study. Residual normal cells were found in both cases. The patients showed a different clinical evolution with a poor outcome for one case and a favorable course of the disease for the other one. The review of the literature in MCL showed a total of 9 inversions affecting different chromosomes. Considering that inversions are very infrequent events in MCL, our findings could be important for detecting genes potentially involved in development and/or progression of this aggressive non-Hodgkin lymphoma subtype.

Constitutional chromosome aberrations as pathogenetic events in hematologic malignancies

A predisposition to tumor development is associated with some constitutional chromosomal abnormalities. Investigations of families with an apparent hereditary cancer and constitutional chromosome rearrangements have led to the molecular identification of tumor suppressor genes. Under the somatic mutation theory for the development of cancer, two mutational events are required. The first step may be a constitutional event and the second an acquired genetic mutation. Cytogenetic studies were performed on 5633 bone marrow specimens from patients with hematologic malignancies from a single institution. Fifty cases of constitutional chromosome aberrations were detected. Data collected from the literature and from our series are reviewed and compared with the incidence of specific constitutional chromosome aberrations in the newborn population. Possible mechanisms that may predispose individuals with constitutional chromosome aberrations to the development of a hematologic malignancy are reviewed.

Inversion of chromosome 12 and lineage promiscuity in hematologic malignancies

Rearrangements of the short arm of chromosome 12 are among the most common aberrations found in hematologic malignancies, including myelodysplastic syndromes, acute myelocytic leukemias, acute lymphoblastic leukemias, and non-Hodgkin lymphomas. We report on a group of 46 patients with a variety of myelocytic and lymphoid malignancies, all with an inversion of chromosome 12. Both pericentric and paracentric inversions occurred. The identified hotspots for breakage were p13 and q24. These correspond to gene-rich areas of known chromosome instability. The inv(12) is difficult to detect and may be misinterpreted as a partial deletion by routine cytogenetics. Fluorescence in situ hybridization studies revised the G-banding interpretations of a deleted 12p in some cases to an inversion. The inv(12) may occur as the sole abnormality in both myelocytic and lymphoid malignancies, suggesting lineage promiscuity as seen with MLL and ETV6 gene disruptions. The majority of patients with the inv(12) had complex karyotypic changes that predicted a poor prognosis. Of the 24 patients with known clinical follow-up, many were refractory to chemotherapy and overall survival was short.

TCL-1, MTCP-1 and TML-1 gene expression profile in non-leukemic clonal proliferations associated with ataxia-telangiectasia

We analyzed the role of 4 genes, TCL-1, MTCP-1, TML-1 and ATM, in the early pathogenesis of T cell leukemia, with particular interest in the characteristics of long-standing non-leukemic clonal proliferations in ataxia-telangiectasia (A-T) patients. Five patients were studied: 4 patients had A-T (2 of whom had non-leukemic clonal proliferations [ATCP]), 1 had B cell lymphoma and 1 had T-ALL; a fifth patient with T-PLL did not have A-T. We measured the levels of expression for TCL-1, MTCP-1 and TML-1. TCL-1, not expressed in unstimulated mature T cells, was upregulated in the peripheral blood leukocytes (PBL) of the 2 A-T patients with ATCP. It was also expressed in the malignant cells of the A-T patient with B cell lymphoma and the T-PLL cells of the patient without A-T. In the same cells, MTCP-1 type A was expressed equally in all 5 patients, as well as in the controls; MTCP-1 type B transcripts were not observed. TML-1, also not expressed in unstimulated T cells, was expressed in the PBL of one A-T patient with ATCP and in the leukemic cells of the non-A-T T-PLL patient. These expression patterns were compared to cellular immunophenotypes. The non-leukemic clonal T cell populations had the characteristics of immature T cells. We conclude that TCL-1 and TML-1 play a role in cell proliferation and survival but are not pivotal genes in the progression to malignancy, even when the ATM gene is mutated. Additional genetic alterations must occur to initiate tumorigenesis.

B-cell acute lymphoblastic leukemia with tandem t(14;14)(q11;q32)

Translocation (14;14)(q11;q32) was associated with acute lymphoblastic leukemia in a child. The B-cell lineage of the leukemic cells led us to perform FISH studies, which showed that the chromosomal breakpoints were telomeric to TCRA/D and IGH loci. These findings show that FISH analyses are necessary when unusual features are associated with a recurrent translocation.

Recurring Structural Chromosome Abnormalities in Peripheral Blood Lymphocytes of Patients With Mycosis Fungoides/Sézary Syndrome

Cytogenetic analysis was performed on peripheral blood lymphocyte cultures from 19 patients with mycosis fungoides (MF )/Sézary syndrome (SS) stimulated with either phytohemagglutinin, a conventional mitogen, or a combination of interleukin-2 (IL-2) plus IL-7. The use of both PHA-stimulated and IL-2 plus IL-7–stimulated cultures enhanced the ability to identify clonal abnormalities. Clonal abnormalities were observed in 11 patients (53%) including one with monosomy for the sex chromosome as the sole abnormality. Five of the 11 patients with clonal abnormalities had normal peripheral white blood cell counts, indicating detectability of clones in the absence of frankly leukemic disease. The presence of clonal abnormalities correlated with advanced stage disease and a significantly reduced survival duration from the time of cytogenetic studies. Clonal abnormalities involving chromosomes 1 and 8 were observed in six cases. In five cases with aberrations of chromosome 1, loss of material involved the region between 1p22 and 1p36. In an additional case, a reciprocal translocation involving 1p33 was observed. Clonal abnormalities involving chromosomes 10 and 17 were observed in 5 cases, clonal abnormalities involving chromosome 2 in 4 cases, and clonal abnormalities involving chromosomes 4, 5, 6, 9, 13, 15, 19, and 20 in 3 cases. In 2 cases a der(8)t(8; 17)(p11; q11) was observed. Regions of the genome that encode T-cell receptors were not involved in abnormalities. The region between 1p22 and 1p36 is identified as a region of the genome that requires detailed analysis toward the identification of potential gene(s) involved in the process of malignant transformation and/or progression in MF/SS.

Classification of peripheral T-cell lymphomas: cytogenetic findings support the updated Kiel classification

The cytogenetic findings in peripheral T-cell lymphomas enabled us to distinguish not only between low and high grade peripheral T-cell lymphomas (PTL) but also between different morphologically defined subtypes. High grade lymphomas exhibited a higher frequency of aberrant clones, polyploid chromosome numbers, a higher complexity of aberrant clones and a lower proportion of normal metaphases than low grade PTL. Moreover, deletions in 6q, trisomies of 7q and monosomy 13 or changes of 13q14 were significantly more frequent in high grade than in low grade PTL. Translocation t(2;5)(p23;q35) was only seen in large cell anaplastic lymphoma. T-CLL/T-PLL was associated with the simultaneous presence of inversion inv(14)(q11q32.l) and trisomy 8q, mostly due to i(8q)(q10). Trisomy 3 was a characteristic chromosome aberration of lymphoepithelioid lymphoma, AILD-type T-cell lymphoma and T-zone lymphoma. In contrast to the other low grade PTL, AILD-type T-ceIl lymphoma and cutaneous T-cell lymphoma showed a high frequency of unrelated clones. In summary, the cytogenetic findings paralleled the histopathologic classification according to the updated Kiel classification and support the value of the distinction of the different morphologically defined entities.

Chromosome aberrations, spontaneous SCE, and growth kinetics in PHA-stimulated lymphocytes of five cases with Sézary syndrome

Cytogenetic studies of five patients with Sézary syndrome (SS) revealed clonal chromosome aberrations in all cases. In one patient, a del(8)(p21) was the sole abnormality, whereas the remaining cases had karyotypes with multiple chromosome changes. In three SS cases with hypodiploid chromosome numbers, structural rearrangements affecting regions 10q22-24 and 12p11-13, and aberrations leading to loss of material from 17p were found concurrently. Bands 14q11 and 14q32 were involved in structural rearrangements in one case each. Our results and review of 51 published previously SS cases that were analyzed with banding techniques indicate that the chromosomes most frequently involved in structural changes were chromosomes 1 and 2 (in 43% of cases), 6 (in 38%), 17 (in 34%), 14 (in 27%), 11 (in 25%), 13 (in 21%), and 9 (in 20%). In particular, the breakpoints tended to aggregate at 1p11, 1p36, 2p11-24, 6q, 9q, 11q, 13q11-14, 14q11, 14q32, and in the pericentric region of chromosome 17. The most common numerical change was loss of chromosome 10, detected in 32% of SS cases. In our studies of three SS cases, sister chromatid exchange frequencies were significantly higher in comparison to the normal control. Cell cycle kinetics analysis revealed that the cell cycle time in the malignant cells was significantly longer than in lymphocytes of normal individuals.

Inversion 14q in acute lymphoblastic leukemia of B-lineage

Many types of leukemia are associated with specific chromosomal rearrangements. Inversion 14(q11q32) has been reported to be specifically associated with post-thymic T-cell malignancies, including T-chronic lymphocytic leukemia. T-prolymphocytic leukemia, and adult T-cell leukemia/lymphoma. We have previously reported its occurrence in T-cell acute lymphoblastic leukemia. Recently, we encountered a case of acute lymphoblastic leukemia with inv(14)(q11q32), which surprisingly showed a B-cell immunophenotype (CD10+CD19+HLA-DR+Ig mu-).

Combined immunophenotyping and karyotyping in peripheral T cell lymphomas demonstrating different clonal and nonclonal chromosome aberrations in T helper cells

Combined immunophenotyping and karyotyping was performed in seven cases of peripheral T cell lymphoma with complex aberrant clones. Various lymphocytic cell populations entered mitosis, whereas all aberrant cells belonged to the T helper/inducer cell population. Lymphomas with the same recurrent chromosome aberrations, i.e. inversion inv(14)(q11q32.1) and isochromosome i(8)(q10), had a very similar immunophenotype. The aberrant cells in these cases expressed CD3+, CD4+, CD7+, CD45RO+. The immunophenotypic similarity is underlined in one case of T prolymphocytic leukemia, in whom the aberrant cells lost the CD8 antigen originally present, during cultivation with PHA. In one case of Sézary's syndrome, two or possibly even three different clones as well as nonclonal aberrations were identified within the T (helper/inducer) cell population, providing further evidence that chromosomal instability is a characteristic feature of cutaneous T cell lymphoma.

Cytogenetic studies in five patients with Sézary syndrome

A cytogenetic study was performed in five patients with Sézary syndrome. Metaphases were obtained from a phytohemagglutinin-stimulated lymphocyte culture. The five patients showed abnormal karyotypes. The chromosomes preferentially involved in numerical aberrations were chromosomes 10 (monosomy) and 13 (monosomy); involved in structural changes were chromosomes 1, 2, 4, 6, and 14. In our series, all patients showed progression of the disease.

Granular lymphocyte proliferative disorders: a multicenter study of 20 cases

A series of 20 patients with granular lymphocyte proliferative disorders (GLPD) is reported. The criterion of inclusion was presence of persistent (> or = 6 months) granular lymphocytosis in the absence of any causative illness. Diagnoses made upon analytical control in half the patients of splenomegaly (25%) and hepatomegaly (25%) were infrequent. Clinical course was nonprogressive in 17/20 patients, but two developed high-grade NHL several years later and one showed progressive disease. Actuarial probability of survival at 5 years was 85%. Granular lymphocyte morphology was relatively homogeneous, and peripheral blood counts were preserved in the most patients. Bone marrow lymphocytic infiltration was low, as assessed by bone marrow aspiration and/or biopsy. Eosinophilia was an outstanding feature in eight cases. Ultrastructurally, all cases showed parallel tubular arrays; cytoplasmic granules and numerous short microvilli were noticed. The lymphoid phenotype was heterogeneous, the most common being CD2+CD3+CD4-CD8+, but six patients (30%) were CD4+ with variable expression of natural killer-associated antigens. Chromosomal analysis was abnormal in 4/10 patients [trisomy 19, t(5;6); inv(14) and inv(10)]. The study of beta-chain of the T-cell receptor revealed clonal rearrangements in 14 (78%), restricted to CD3+ patients (92%). In vitro culture of myeloid precursors showed decreased CFU-GM in 5/6 patients. Virological studies for HTLV-I and II were negative. In conclusion, the presence of a clonal proliferation was not correlated with the clinical course or an associated disease.

Trisomy 8q due to i(8q) or der(8) t(8;8) is a frequent lesion in T-prolymphocytic leukaemia: four new cases and a review of the literature

Cytogenetic abnormalities found in four cases of T-cell prolymphocytic leukaemia (T-PLL) are described. An isochromosome 8q was found in three patients and a t(8;8) in one. In the four cases, karyotypes were complex and showed a high degree of instability. In addition, we reviewed 27 published cases of cytogenetically studied T-PLL. On the whole, the most frequently recurring anomalies in T-PLL are 14q lesions with nonrandom breakpoints, inversion (14)(q11q32) or tandem translocations (14;14) (not seen in any of our cases) and trisomy for 8q. mainly due to i(8q), found in more than 40% of patients each. Similar structural anomalies were found almost as frequently among the 23 cytogenetically studied cases of so-called T-chronic lymphocytic leukaemia (T-CLL) reported prior to 1989. It is now accepted that the T-cell counterpart of B-CLL either does not exist or is exceedingly rare and thus previously reported cases of T-CLL sharing the chromosomal characteristics of T-PLL may well have been misdiagnosed examples of T-PLL. Isochromosomes 8q are exceptionally found in other types of haematological malignancies. However, i(8q) could not be shown to be the primary lesion in any case in T-PLL and the role of trisomy for 8q, as well of the associated monosomy 8p, is entirely unknown.

Clonal t(8;14)(p11;q31) in a case of reactive lymphoproliferation

A clone with an unbalanced translocation t(8;14)(p11;q31), resulting in deletion of the distal part of the long arm of chromosome 14, 14q31 --> 14qter, was detected in a case of Piringer's lymphadenitis. Histopathologically no atypical cells or other signs of malignant lymphoma were found. Southern blot analyses showed no rearrangement of the immunoglobulin heavy chain gene (IGH) or the T-cell receptor gamma chain (TCRG) gene. The case exemplifies that the detection of a chromosomally aberrant clone does not necessarily prove that a lymphoproliferative process is malignant.

Cytogenetics in the investigation of haematological disorders

Chronic and acute, myeloid and lymphatic haematological neoplasms are characterized by acquired genetic rearrangements that, in the majority of cases, can be detected as clonal chromosomal abnormalities. The aberrations are either primary, meaning that they contribute to the establishment of the neoplasm, or secondary, in which case they are acquired during the clonal evolution and malignization of the neoplastic cells. The abnormalities are non-randomly distributed; the aberration pattern differs from disease to disease and sometimes is so characteristic that individual rearrangements may be virtually pathognomonic for particular neoplasms. The cytogenetic characterization of haematological malignancies is of two-fold importance. First, the recurrent aberrations provide us with an insight into the pathogenetic mechanisms that are operative. They pinpoint those areas of the human genome that carry genes or regulatory sequences whose function is disturbed in leukaemias and lymphomas. Using DNA recombinant techniques in addition to chromosome-level investigations of these cancer-associated rearrangements, the molecular pathology of leukaemias and lymphomas is now gradually being unravelled. Second, even before the long-term goal of a more fundamental understanding of the neoplastic process is reached, the cytogenetic aberrations have a direct clinical importance. The finding of an acquired, clonal chromosome abnormality in haematopoietic cells (-Y in old men is an exception) means that the patient has a neoplastic disease. Often, but by no means always, the type of aberration is also informative as to which type of neoplasm is present. During therapy, remission and relapse can be monitored by cytogenetic analyses. Finally, the karyotypic pattern influences prognosis and may thus be taken into account when the choice of therapy is made.

Recurrent chromosomal aberrations in peripheral T-cell lymphoma

Histological, immunological, and cytogenetic analysis of the same neoplastic tissues have been performed on seven patients with peripheral T-cell lymphomas (PTCL). Clonal chromosomal abnormalities in five cases are reported. The most common chromosomal aberration, observed in four patients, is a rearrangement of chromosome 14 with a breakpoint in q11.2. Aberrations of chromosome 8 also occurred in four patients, three of whom had an extra 8q. The data indicate that breakpoints of malignant diseases affecting similar cell types might cluster to specific chromosomal regions, which can be helpful in recognition and classification of PTCL.

Chromosomal abnormality limited to T4 lymphocytes in a patient with T-cell chronic lymphocytic leukaemia

Cytogenetic, immunologic and DNA studies were performed on a patient with the T-cell type of chronic lymphocytic leukaemia. Standard G-banding karyotype analysis revealed clonal chromosome abnormalities with the karyotype 42-44,XY,-11,-12,-13,-16,-21,-22,i(8q),inv(14) (q11q32), t(15;?)(p11;?), +4-6mar/43-44,X,t(Y;14)(p11;q11),-11,-12, -13,-21,-22,i(6p),i(8q),inv(14)(q11q32),t(15;?)(q11;?), +1-3mar. MAC (morphology, antibody, chromosomes) methodology, which allows the immunophenotyping of mitotic cells, showed that the chromosome abnormalities were restricted to CD4-positive helper/inducer T lymphocytes and that CD8 suppressor/cytotoxic T cells and B lymphocytes possessed a normal karyotype. The results also indicate that the proportion of abnormal metaphases and the overall mitotic activity after 3.5 days of stimulation in vitro were highest when PHA and TPA were used as mitogens. When the culture period in the presence of PHA + IL-2 was extended, the proportion of the abnormal cell population decreased in direct relation to the length of the culture period, ranging from 100% at 3.5 d to 0% at 31 d after stimulation. Southern blotting analysis revealed rearrangements of both the immunoglobulin heavy chain gene and the beta T-cell receptor gene.

Inv(14) with distal breakpoint in 14q32.1 in three cases of T cell lymphoma

The distal breakpoint of inv(14) in T cell clones, established from patients with ataxia telangiectasia, lies outside the immunoglobulin heavy chain gene locus on 14q32.3, and more proximal to the centromere than the distal breakpoint of inv(14) in the T cell lymphoma cell line SUP-T1. We report 3 cases of T cell lymphoma cytogenetically showing the same type of inv(14) as the AT T cell clones. All 3 cases express a similar immunophenotype, which is that of peripheral T lymphocytes with phenotypic remnants of thymic or postthymic lymphoblasts. This finding provides evidence that this type of inv(14) is involved in the malignant transformation of mature T lymphocytes.

Cytogenetic study of a patient with the Sézary syndrome

A cytogenetic study was performed in a patient with Sézary syndrome, which is a T-helper lymphoproliferative disorder. Metaphases were obtained from a phytohemagglutinin-stimulated lymphocyte culture. Normal, hypodiploid (42 to 45 chromosomes) and hypotetraploid (84 to 88 chromosomes) cells were observed. Both abnormal cell lines showed the same abnormalities involving chromosomes 1, 2, 4, 6, 10, 11, 12, 14, 16, and 20.

Primary chromosome abnormalities in human neoplasia

At the cellular level, cancer is a genetic disease; genetic changes in somatic cells are essential events in neoplasia. In a majority of cases these changes involve large enough blocks of genetic material to be visible in the microscope. The chromosome aberrations in neoplastic disorders are probably of three kinds: (1) primary abnormalities, which are essential steps in establishing the tumor; (2) secondary abnormalities, which develop only after the tumor has developed, but which nevertheless may be important in tumor progression; and (3) cytogenetic noise, which is the background level of nonconsequential aberrations. These latter changes are, in contrast to the primary and secondary changes, randomly distributed throughout the genome. The primary abnormalities, of which several dozens have now been identified, are mostly strictly correlated with particular diseases and even with histopathological subtypes within a given disease. This has been evident in the leukemias for some years already, and information now accumulating on solid tumor karyology indicates a similar situation. Clonal chromosome abnormalities are a feature of both benign and malignant neoplasms, although the changes are often less massive in the former. Apart from being clinically useful as a diagnostic technique and an aid in prognostication, tumor cytogenetics also plays a role in identifying those genomic sites which harbor genes essential in the pathogenesis of neoplastic lesions. So far, two functionally different classes of directly cancer-relevant genes have been detected, the oncogenes and antioncogenes. There is every reason to believe that future investigations with cytogenetic and recombinant DNA methods will add to our knowledge of the biology of human neoplasia, in those tumor types where the characteristic genetic change is already partially known, and by identifying hitherto unknown karyotypic abnormalities.

Cytogenetic studies on the adult T-cell leukemia in Japan

Cytogenetic studies were performed on 16 patients with ATL seen in Northern Kyushu island; nine were patients with acute type leukemia, one with crisis type and five with lymphoma type. The serum antibody for HTLV-1 (ATLA) was positive in all patients and the phenotype of ATL cells were ERFC+, OKT3+, OKT4+, OKT6-, OKT8-, OKT10+, OKla1+/- and Tac+. Abnormal findings of chromosomes were observed in 15 patients. Thirteen patients were in near diploid range. One patient was in triploid range and one patient was in tetraploid range. The polyploid karyotypes were found only in lymphoma type patients. Trisomy 3 and trisomy 7 were observed each in three patients with acute type of ATL. The most frequent abnormal rearrangement was observed in the long arm of chromosome 6 and the break occurred at band 6q15 and 6q21 each in four patients in this series.

Analysis of a T-cell tumor-specific breakpoint cluster at human chromosome 14q32

Cytogenetic abnormalities involving chromosome 14 band q32 are consistently observed in human T-cell tumors. Patients with ataxia-telangiectasia (AT) are especially prone to development of these tumors, which frequently carry either inversion inv(14)(q11;q32) or translocation t(14;14) (q11;q32) chromosomes. We have previously shown that the cytogenetic breakpoints of one t(14;14)(q11;q32) chromosome and two inv(14)(q11;q32) chromosomes in T-cell tumors from AT and non-AT patients join the T-cell receptor alpha chain locus, at chromosome band 14q11, with a region(s) at 14q32 centromeric of the immunoglobulin heavy chain variable region (VH) gene IGHV. We now show that these two inv(14) breakpoints are linked by 2.1 kb of germ-line 14q32 DNA and that the three breakpoints define, by in situ hybridization analysis, a single locus at chromosome band 14q32.1 located about 15-20 million base pairs on the centromeric side of the IGH locus. Sequence analysis of the 14q32.1 breakpoint regions indicates that abnormal recombination does not universally result from mistaken V-D-J joining (D = diversity region; J = joining region). Therefore, we invoke a tumor selection model to describe the role of the 14q32.1 locus in tumor development.

Cytogenetics of T-cell malignant lymphoma. Report of 17 cases and review of the chromosomal breakpoints

Cytogenetic studies are reported on 17 T-cell malignant lymphomas (ML) including six cutaneous T-cell malignant lymphomas (CTCL). Due to the low incidence of rearrangements on bands where the T-cell receptor genes are located, other cases reported in the literature were analyzed in order to estimate the most frequent chromosomal breakpoints in ML, CTCL, and adult T-cell leukemia-lymphoma. Besides chromosomes 1 and 6q, 14q11, 7p15p21, and 7q32q35, the most frequent rearrangements involved bands 14q32, 2p11-p14, 2p23-p25, 17cen, 9p21p23, and 10p13p15. These results show that molecular studies must be concentrated on these chromosomal regions in order to identify the DNA sequences that may be involved in T-cell malignancies.

Cytogenetic study of chronic lymphocytic leukemia in ten Japanese patients with a case of the same chromosome abnormality both in T and B cells

Peripheral blood lymphocytes from ten patients with chronic lymphocytic leukemia (CLL) stimulated with phytohemagglutinin (PHA), pokeweed mitogen (PWM), Epstein-Barr virus (EBV), and T-cell growth factor were studied cytogenetically. Eight of ten cases were clinically and immunologically B-cell CLL, and two cases were T-cell CLL. Chromosome analysis revealed that one patient, diagnosed as B-cell CLL, had a clonal abnormality in the leukemic cells. The abnormal karyotype was 46,XY,+3,-15,t(10;19)(q22;p13),t(11;14) (q13;q32),13q+,17q-. The frequencies of the abnormal cell stimulated with PHA, PWM, and EBV were 50%, 13%, and 100%, respectively. Finding the same clonal abnormality after stimulation with three different mitogens suggests that the factor responsible for the development of CLL might affect the stem cell common to T-cell and B-cell lymphocytes. In cells with this abnormal karyotype, chromosome 13q+ seems to have a homogeneous staining region. In the present series of B-cell CLL, no trisomy 12 known to be the specific chromosome abnormality was observed.

Genetic markers on chromosome 7

Chromosome 7 is frequently associated with chromosome aberrations, rearrangements, and deletions. It also contains many important genes, gene families, and disease loci. This brief review attempts to summarise these and other interesting aspects of chromosome 7. With the rapid accumulation of cloned genes and polymorphic DNA fragments, this chromosome has become an excellent substrate for molecular genetic studies.

What's new in lymphoma cytogenetics?

Non-random chromosome abnormalities have been found in all types of malignant lymphomas. It is obvious that some cytogenetic abnormalities are associated with certain morphological types. Thus, among the Burkitt's lymphomas the 2;8-, 8;14- and 8;22-translocations are found in the great majority of cases; t(14;18) is associated with follicular lymphomas; +12 and t(11;14) with well differentiated lymphomas; and rearrangements of 14q11 and trisomy 3 with T-cell lymphomas. The molecular changes involving the c-myc oncogene and the immunoglobulin loci in Burkitt's lymphoma have been intensively studied. Among other non-Hodgkin's lymphomas the molecular mechanisms behind t(11;14) and t(14;18) in B-cell lymphomas and 14q11 rearrangements in T-cell lymphomas are starting to be unravelled. A number of other aberrations, such as +3, 6q-, and +12, have been associated with non-Hodgkin's lymphoma although the molecular mechanisms behind these rearrangements are still unknown. Very little is known about clinicocytogenetic correlations, but some observations clearly indicate that the karyotypic pattern is an important prognostic factor in non-Hodgkin's lymphoma. Contrary to non-Hodgkin's lymphoma, very little is known about the cytogenetic findings in Hodgkin's disease. The sparse results, however, indicate that there are similarities to those in non-Hodgkin's lymphoma.

Acute leukemia of megakaryocyte lineage with tumor formation. An autopsy case of patient with Down's syndrome

In this report we present the autopsy findings of acute megakaryoblastic leukemia with tumor formation in a 2-year-old female infant with Down's syndrome. Chromosomal analysis of blast cells revealed constitutional anomaly of trisomy 21 and two other related types of abnormal clones. Flow cytometric examination revealed blast cells expressing Ia-like or HLA-DR antigens. Postmortem examination showed extensive infiltration of leukemic cells in most of the examined organs, including the bone marrow with myelofibrosis. Tumor masses in the maxillary, frontal and femoral bones and the atria of the heart had undergone massive infiltration of atypical blast cells with an increase in the reticulin network. The final diagnosis was confirmed by ultrastructural cytochemistry of the platelet peroxidase reaction as well as by immunological staining utilizing anti-platelet glycoprotein IIb/IIIa, antiplatelet factor 4 and anti-beta-thromboglobulin antibodies for the blast cells. It seems likely that platelet-derived growth factor, secondary to an increase in the reticulin network, plays a major role in myelofibrosis of acute megakaryoblastic leukemia with tumor formation.

Cytogenetic studies in T-cell malignancies

Clonal chromosome abnormalities in ten cases of T-cell lymphoproliferative disorders are reported. In addition, an extensive review of the literature on T-cell lymphomas shows the chromosomal sites most frequently involved in structural rearrangements.

Three consecutive primary malignancies in one patient during childhood

Patients with a primary immunodeficiency syndrome have an increased risk of developing a malignancy. Lymphoreticular malignancies are the most common malignancies in these patients. Patients with ataxia telangiectasia (AT) also appear to be at a high risk for the development of nonlymphoid tumors--in particular, carcinomas of the gastrointestinal tract and central nervous system tumors. We describe a child with an immunodeficiency and slight neurological manifestations. During childhood she developed three consecutive primary malignancies.

Cytogenetic studies on human myeloma cell lines

Cell lines (U-266, U-1957, U-1996 and U-2030) established from 4 patients with multiple myeloma (MM) were analyzed cytogenetically. The cell lines represent different stages in B-cell differentiation as evidenced by ultrastructural and functional characteristics. The karyotypic pattern in 3 newly established myeloma lines was studied after a few months in culture and compared to the old myeloma cell line U-266, which was examined after 6, 7 and 8 years of continuous cultivation. Frequency of progressive numerical and structural aberrations during long-term cultivation and their correlation with alterations in growth properties were addressed. We describe the presence of a high frequency of both numerical and structural chromosomal abnormalities in the cells of all 4 myeloma lines studied. Chromosomes often associated with structural abnormalities were 1, 3, 6, 12 and 14. A 14q + marker chromosome was detected in 2 of the 4 cell lines. The breakpoints on the chromosomes participating in structural aberrations in myeloma exhibit some correlation to chromosome sites at or close to locations of mapped oncogenes. No translocations of c-myc were found. These data were further supported by Southern blot analysis (unpublished data). The extent of numerical, but not structural, aberrations correlates with the differentiation stage of the myeloma lines in that the 2 mature lines U-266 and U-1957 were both near-diploid. Multiple progressive chromosomal changes have emerged in U-266 during a period of 8 years with development of independence of feeder cells and increased growth rate. However, capacity for production of complete Ig molecules has remained stable.

Cytogenetic and immunologic characterization of mitotic cells in chronic lymphocytic leukaemia

Lymphocytes from 14 patients with chronic B-cell leukaemia (B-CLL) and one with chronic T-cell leukaemia (T-CLL) were studied by the MAC (Morphology, Antibodies, Chromosomes) method, which allows simultaneous analysis of the morphology, immunologic phenotype and karyotype of the same mitotic cell. Use of the MAC-method in present studies has yielded new information about the cytogenetics of CLL. Although most of the interphase cells from patients with B-CLL were positive for B-cell markers, many of the mitotic cells turned out to be T cells, supporting the notion that the cells studied by conventional chromosome analysis are often non-neoplastic T cells. In some B-CLL cases with normal karyotype in the conventional chromosome study, however, most of the mitotic cells were B cells, indicating that neoplastic B cells may also have a normal karyotype. The patient with T-CLL had normal karyotype even though most of the mitoses were T cells. The chromosome abnormalities found were restricted to cells with light chain clonality. Our results show that clonal chromosome abnormalities do occur in neoplastic B cells of patients with B-CLL.

Role of chromosomal abnormalities in chronic lymphocytic leukemia

Chromosomal aberrations occur in both B-CLL and T-CLL. The polyclonal B-cell mitogens, in particular Epstein-Barr virus and lipopolysaccharide from E. coli, have been used successfully to reveal chromosomal abnormalities in 40-60% of patients with B-CLL, while T-cell mitogens have shown chromosomal aberrations in T-CLL. The most common clonal chromosomal aberration in B-CLL is an extra chromosome 12, alone or together with other abnormalities. Other common aberrations are 14q+, structural aberrations on 6, 11, 12 and 13. Proto-oncogenes are frequently located close to breakpoints. The proto-oncogene c-K-ras is located on chromosome 12 and an abnormal transcript has recently been implicated in a subset of B-CLL-patients. An extra chromosome 12 as well as multiple chromosomal abnormalities in B-CLL appear to predict a less favourable prognosis. T-CLL is in most patients characterized by an inv(14), an extra 8q and structural abnormalities in chromosome 7. The genes for the specific T-cell receptor as well as the immunoglobulin heavy chain are located on these chromosomes. Chromosomal aberrations appear to have pathogenetic importance in both B-CLL and T-CLL.

Growth of large chromosomally abnormal T cell clones in ataxia telangiectasia patients is associated with translocation at 14q11. A model for other T cell neoplasia

Human T cell malignancies often show chromosome breaks at 14q11, within the alpha chain locus of the human T cell antigen receptor, with translocation of the distal portion of 14 to one of several sites. In patients with ataxia telangiectasia (A-T) the majority of T cell chromosome translocations associated with this disorder appear to occur at the sites of the T cell antigen receptor genes 7p14, 7q35, and 14q11 and may result in clone formation. In three large proliferating A-T T cell clones we have observed (including one which became malignant) and in most T cell tumours reported, the clonal chromosome exchange involves one breakpoint at 14q11 with the second breakpoint occurring in a gene not involved in the immunoglobulin supergene family. Our observations on A-T patients confirm the suggestion that chromosome exchanges involving either t(7;14)(p14;q11), t(7;14)(q35;q11), inv(7)(p14q35), or t(7;7)(p14;q35) confer only a small proliferative advantage on T cells in vivo without the capacity for malignant transformation and that the potential for malignant change is not a feature of all these rearrangements, but is restricted to cells or clones with other chromosome exchanges.

Cytogenetic studies of Sézary cells

Cytogenetic studies of two patients with Sézary's syndrome and of one patient with mycosis fungoides are reported. One chromosome #14 at band 14q11 was involved in chromosomal rearrangements in one patient. A review of previously reported cases shows that some chromosome abnormalities appeared nonrandomly, involving chromosomes #1, #4, #6, #7, #9, #13, #14, and #17. Abnormalities on 2p and monosomy 10 were emphasized.

Chromosomal abnormalities in non-Hodgkin lymphoma with peripheral T-cell type: effect of HTLV-I infection

Cytogenetic studies were done in lymph node and peripheral leukemic cells from sixteen patients with non-Hodgkin lymphoma with peripheral T-cell type. Ten patients were positive for human T-cell leukemia virus I (HTLV-I) proviral DNA in tumour cells and six were negative. The former group had a higher tendency for leukemic conversion and poorer prognosis than the latter. However, no definite difference on the numerical and structural chromosomal abnormalities between these two groups was found. The most frequent chromosome abnormalities: 14p+, 14q+ and No. 6 abnormalities were detected in both groups. These results may indicate that HTLV-I does not play a specific role in chromosome abnormalities of non-Hodgkin lymphoma with peripheral T-cell type.