Two complex translocations in chronic granulocytic leukemia involving chromosomes 22, 9, and a third chromosome

Impact of Imatinib on reducing the painful crisis in patients with sickle cell disease

INTRODUCTION

Sickle cell disease (SCD) is a common hemoglobinopathy worldwide that causes painful crises and hospitalization of patients. These attacks decrease survival and cause chronic end-organ damage in these patients.

HYPOTHESIS

For this reason, finding new treatment approaches could be helpful.

METHOD

In this study, Imatinib was applied as a mast cell inhibitor to reduce pain crises in these patients. Seven patients resistant to hydroxyurea and folic acid treatment and who had at least four painful crises per year with hospitalization were enrolled in this study with treatment with Imatinib (100 mg, twice daily). Subsequently, the number and duration of hospitalizations, analgesic requirement, the severity of chronic pain, and changes in the hematological parameters of these patients were evaluated before and after the treatment.

RESULTS

The data showed that the total number of hospitalizations and the entire duration of hospitalizations were reduced 16 times after treatment with Imatinib, without apparent changes in hematological parameters. Also, the demand for pethidine, tramadol, and nonsteroidal anti-inflammatory drugs (NSAIDs) was reduced in all patients. The average reduction in chronic pain was over 70%.

CONCLUSION

This study demonstrates that treatment with Imatinib in patients with SCD or sickle cell anemia (SCA) may be a suitable therapeutic option for reducing painful crises.

t(3;9;22) 3-way chromosome translocation in chronic myeloid leukemia is associated with poor prognosis

Chronic myelogenous leukemia (CML) is genetically characterized by the reciprocal translocation of chromosome 9 and 22. Around 5-8% of CML develop complex variant Ph translocations involving one or more chromosomal regions besides 9 and 22. Chromosome 3 is not frequently involved in complex translocations in CML. We report in this study a case of CML displaying a t(3;9;22) 3-way translocation. A review of the literature appears to indicate that CML patients with this translocation tend to have an aggressive course and poor outcome. Additional 3-way chromosome translocations associated with CML are also reviewed.

The role of LMO2 in development and in T cell leukemia after chromosomal translocation or retroviral insertion

Chromosomal translocations are primary events in the development of leukemias, representing at least one genetic feature of the putative cancer stem cell. Studies of genes influenced by chromosomal translocations have yielded a vast amount of information about how cancer is initiated and maintained. In particular, acute leukemias have demonstrated that chromosomal translocations often involve transcription regulators that function by interacting with proteins and by controlling cell fate in the aberrant setting of the developing cancer cell. As a quintessential chromosomal translocation gene product, LMO2 has many properties that typify this class of molecule. In addition to its involvement in chromosomal translocations, the LMO2 gene was inadvertently activated in an X-SCID gene therapy trial by retroviral insertion. New molecular therapies targeted directly at the LMO2 protein could have major impact as adjuncts to existing therapies or as therapeutics in their own right. In this review, we outline the current knowledge about LMO2 and some possible routes to develop reagents that might be possible macromolecular drugs in the future.

Malignancy in patients with sickle cell disease

Malignancy in patients with sickle cell disease (SCD) has been previously reported, but the types of cancer and its incidence remain undefined. With the advent of hydroxyurea therapy, there is concern about increasing the cancer risk for patients with SCD. The International Association of Sickle Cell Nurses and Physician Assistants identified 52 cases of cancer (49 patients) among 16,613 patients with SCD followed at 52 institutions. The median age at malignancy diagnosis was 34 years (range, 14 months-62 years). Twenty-one cases (40%) occurred in pediatric patients, primarily leukemia (n = 7) or Wilms' tumor (n = 5), with 15 children surviving. Most adults had solid tumors, especially carcinomas, and only nine were known to be alive. Three patients received hydroxyurea before the diagnosis of malignancy. These data provide essential baseline information for the accurate interpretation of future reports of malignancy in patients with SCD, especially those receiving hydroxyurea therapy.

Entendendo o Processo Molecular da Tumorigênese

Nos últimos 25 anos, o reconhecimento dos mecanismos genético-moleculares implicados na gênese e na progressão do câncer tem permitido obter novos métodos de diagnóstico e de acompanhamento, redirecionando de forma drástica a terapêutica do paciente com neoplasia. Alguns marcadores moleculares já estão sendo utilizados na rotina e deverão prover testes sensíveis e específicos para o diagnóstico precoce, estadiamento e acompanhamento do paciente com câncer. As características moleculares de cada tumor deverão permitir predição do seu comportamento, ajudando a delinear estratégias terapêuticas mais efetivas. Apresentamos de forma didática os principais mecanismos controladores do ciclo celular e do crescimento, definindo a importância de oncogenes erroneamente ativados e de genes supressores tumorais perdidos ou não-funcionantes, dos genes envolvidos na programação e manutenção da vida celular e de outros genes que atuam no processo de tumorigênese. Os mecanismos de progressão tumoral, invasão e metastatização à distância são revistos enfatizando-se a aplicação prática do conhecimento a respeito de tais mecanismos. Lembramos o papel da instabilidade genética e dos fenômenos epigenéticos na definição fenotípica do câncer, sugerindo as aplicações da genética molecular na terapia gênica do câncer.

Ph-negative T cells in a patient with chronic myelogenous leukemia for twenty-eight years

The frequency of metaphases without a Philadelphia chromosome was determined in mitogen-stimulated cultures of peripheral blood mononuclear cells (PBMC) and purified T lymphocytes (93% CD2-positive) from a patient with chronic myelogenous leukemia (CML) for 28 years. The PBMC cultures contained few Ph-negative cells (8%), but they constituted 92% of the metaphases in T cell cultures, indicating few if any Ph-positive T cells in the patient's circulation. The results demonstrate that T cells derived from the leukemic clone may fail to replace the non-neoplastic population even when CML arises in childhood and the patient survives for many years. This raises questions concerning the normal role of the bone marrow as a source of T cells after infancy, and also whether Ph-positive lymphocytes may be at a disadvantage for growth.

Karyotypic stability in chronic B-cell leukemia

Twenty-one patients with B-cell chronic lymphocytic leukemia (B-CLL) have been followed for more than 2 years with serial cytogenetic studies, including 11 cases for more than 5 years and three others for more than 10 years. A chromosomally abnormal clone was present at the time of initial study in 10 of these patients, and neither these nor the 11 individuals with a normal karyotype had any cytogenetic evolution during the follow-up period, although clinical progression, requiring therapy, was observed in 13 cases. In an additional 12 B-CLL patients who had repeat chromosome studies but were followed for less than 2 years, two patients with advanced disease and multiple cytogenetic abnormalities developed minor additional karyotypic changes and died within 18 months, and two patients with a normal karyotype developed rapidly progressive disease associated with an emerging chromosomally abnormal clone and survived only 1 year. These results demonstrate that karyotypic evolution is rare in B-CLL. Its occurrence indicates a poor prognosis, but its rarity suggests that clinical progression in this disease is usually more dependent on other factors.

Genomic diversity of Philadelphia-positive chronic myelogenous leukemia

The incidence of breakpoints in CML patients with variant translocations was investigated. There was no relationship between the length of various chromosomes with breakpoint frequency. However, a significantly higher (p less than 0.05) incidence of breaks were seen on the long arms as compared to the short arms due mainly to the involvement of 9q and 22q in these translocations. Chromosome 17 showed a significantly (p less than 0.005) higher involvement in these translocations, however only when 9q34-qter was not cytogenetically involved. A total of 683 breaks were found in 225 cases. 362 of these were located at c-abl and c-sis, while 110 were at other oncogenetic sites. The prognostic and hematologic features of patients with variant translocations are not significantly different from those of CML cases with the typical 9q;22q translocation. Some of these complex translocation, where the breakpoints are correlated with oncogenetic sites, are further discussed in molecular terms.

Hematologic malignancy in sickle cell disease: report of four cases and review of the literature

Hematologic malignancy has rarely been reported in adults with sickle cell disease. We describe four sickle cell patients (two with hemoglobin SC, two with hemoglobin SS) who developed hematologic malignancy (acute myeloblastic leukemia, multiple myeloma, malignant histiocytosis, and Hodgkin's disease). Three of the cases represent the first adult association between SC or SS hemoglobinopathy and the particular malignancy involved. Sickle hemoglobin does not appear to exert a protective effect against childhood hematologic malignancies, suggesting that better survival in sickle cell disease may be accompanied by an increased incidence of hematologic neoplasms in adulthood. Karyotypic analysis revealed alterations of chromosome 5 in two sickle cell patients with leukemia, raising the possibility of a chromosomal link between the two diseases. Further epidemiologic and cytogenetic studies are needed to define the relationship between hematologic malignancy and sickle cell disease.

Cytogenetic pattern in leukemic cells of patients with constitutional chromosome anomalies

Acquired karyotypic changes analyzed by banding techniques in 21 patients with a malignant hematologic disorder and a major constitutional chromosome anomaly, including ten patients with trisomy 21, five patients with a balanced translocation, and six patients with a sex chromosome anomaly. Detailed karyotypic findings were ascertained in 28 additional patients reported in the literature. Some striking differences were observed in the combined material of the present series and cases previously published as regards (a) distribution of morphological leukemia types among patients with different types of constitutional anomalies, and (b) incidence and type of acquired chromosomal abnormality among patients with different types of constitutional anomalies.

XX T cells and XY B cells in two patients with severe combined immune deficiency

Immunologic evaluation of two unrelated male infants with clinical and laboratory evidence of severe combined immunodeficiency (SCID) revealed T cells with a mature phenotype in the peripheral circulation of both patients although both had biopsy evidence of thymic alymphoplasia. Both had a normal number of T cells with a cytotoxic/suppressor surface marker (OKT8) but very few T helper cells (OKT4). Lymphocyte stimulation with the mitogens PHA, Con A, and pokeweed or with allogeneic cells resulted in no proliferation. However, addition of T cell growth factor, plus the phorbol ester TPA, to lymphocytes cultured with the T cell mitogen PHA did result in some proliferation of T cells. In both cases these T cells demonstrated an XX female karyotype and were probably of maternal origin. In contrast, proliferating B cells stimulated with Epstein-Barr virus demonstrated a normal XY male karyotype. The possibility that severe combined immune deficiency in these patients was the result of graft-versus-host disease induced by maternal lymphocytes is discussed.

Two adult siblings with thrombocytopenia and a familial 13;14 translocation

A woman with thrombocytopenia that progressed to aplastic anemia, and her brother, who had persistent thrombocytopenia, both had a constitutional t(13;14) translocation. Six other family members, in three generations, had the same translocation, but no hematologic disorder. There was evidence suggestive of increased chromosomal fragility in lymphocyte cultures from two members of the kindred, but not in the two patients. The findings support a postulated association between the t(13;14) and hematologic disorders, but whether the mechanism involves an inherited defect in chromosomal stability is unproved.

Cytogenetics of childhood preleukemia

Chromosome studies were done on ten children with childhood preleukemia characterized by anemia, thrombocytopenia, blasts in the circulation, and hypercellular marrow with excess blasts. The syndrome was clinically similar to adult preleukemia (myelodysplastic disorder). A chromosomally abnormal clone was found in the marrow in five patients: three with monosomy 7; one with a chromosome No. 21 replaced by two isochromosomes for 21q; and one with multiple alterations including an extra, abnormal chromosome No. 7. It was not apparent that a karyotypic change indicated a worse prognosis. The observed chromosome abnormalities appeared to overlap less with those in acute nonlymphocytic leukemia occurring de novo than is the case in adults, perhaps reflecting differing contributions of genetic and environmental factors to the pathogenesis of the disease at different ages.

The clinical and cytogenetic significance of C-banding on chromosome #9 in patients with Ph1-positive chronic myeloid leukemia

The C-band polymorphism of chromosome #9 in 18 patients with chronic myeloid leukemia (CML) with a Philadelphia chromosome (Ph1) translocation between chromosomes #9 and #22 was examined using C- and Q-banding techniques on the same metaphases and the classification proposed by Patil and Lubs [1]. The C-band polymorphism of chromosome #9 in CML was found not to differ in leukemic cells with the Ph1 and phytohemagglutinin-stimulated lymphocytes without the Ph1 and to have a clonal origin, i.e., to arise from a single cell in which the Ph1 translocation has taken place. A comparison of the C-band polymorphism of chromosome #9, survival after diagnosis of the disease, and abnormal chromosomes in addition to the Ph1 indicates some interesting aspects. Patients with the smallest C-band (level 1) on chromosome #9 not involved in the Ph1 translocation and with a relatively large C-band (level 2) on chromosome #9 with the Ph1 translocation (C9-1,2) tend to have no clonal evolution and short survival after diagnosis of the disease. On the other hand, patients with other types of C-band patterns tend to have evidence of clonal evolution and long survival. This study suggests that the C-banding pattern in Ph1-positive CML might be utilized as a prognostic parameter in the disease and that the C-segment might have biological activity.

"Masked" Ph1 chromosome in a complex three-way translocation

A patient with myelofibrosis was found to have a 46,XX,del(1)(q24),del(11)(p11),-22,+mar karyotype in unstimulated peripheral blood (PB) and spleen cells. On detailed cytogenetic examination it was determined that this patient had an apparently "masked" Ph1 chromosome contained in a complex three-way translocation. Since phytohemagglutinin (PHA)-stimulated PB and spleen cells were essentially normal, the masked Ph1 chromosome was assumed to be an acquired cytogenetic abnormality. The portion missing from the masked Ph1 chromosome was apparently translocated onto del(1). Thus, the detailed karyotype was 46,XX,t(1;11;22)(q24;p11;q11 or q12),t(1;22)(q24;q11 or q12). This complex rearrangement was present primarily in cells belonging to the granulocyte-macrophage cell lineage, whereas E-rosetting cells, and presumably T lymphocytes, had normal karyotypes.

Variant Ph1 translocations in CML and their incidence, including two cases with sequential lymphoid and myeloid crises

A serial cytogenetic study of 110 cases of chronic myelogenous leukemia (CML) has been performed with G- and/or Q-banding techniques with the following results. (1) Seven out of the 110 cases were karyotypically normal. (2) A variant Ph1 translocation was observed in three cases. In one case, the leukemic cells contained two reciprocal translocations, i.e., a t(3;9) (q21;q34) and a t(17;22)(q21;q11); therefore, a Ph1 chromosome was masked by a translocation of the deleted material from the 17q onto the band q11 of the long arm of a chromosome No. 22. In the second case, a variant Ph1 translocation involved chromosomes No. 9, 20, and 22, resulting in a karyotype interpreted as 46,XX,t(9q+;20q+;22q-); in this rearrangement, one of the segments, i.e., 9q31 or 9q33, seemed to be interstitially deleted and inserted into the interstitial region (q11) of a chromosome No. 20 and the 22q11 leads to qter was translocated onto the 9q. This is the first case in which chromosome No. 20 was involved in a variant Ph1 translocation. In the third case, the karyotype of leukemic cells was interpreted as 46,XX,t(5;9;22)(q13;q34;q11). (3) The frequency of Ph1-negative CML and that of Ph1-positive CML with various types of Ph1 translocation from 15 studies reported as series of 25 or more cases, including the present study, have been tabulated. The incidence of a variant Ph1 translocation was 4.1% (42/1027 cases of Ph1-positive CML); of the 42, 13 were of a simple type and 29 of a complex type. (4) In one case of the present study, a masked Ph1 by a translocation of material onto the short arm of the 22q- was observed in the blastic crisis but not in the chronic phase. From the present study and a review of the published cases, it appears that the incidence of such a "masked" Ph1, which cannot be detected by conventional Giemsa staining, is less than 0.6% in CML cases. (5) The first and the second cases with a variant Ph1 translocation mentioned above developed a myeloid blastic crisis after the induction of remission of a lymphoid blastic crisis. For the present, it is unclear whether the occurrence of such blast cells in the two cases and the cytogenetic findings are coincidental. However, the evidence supports the notion of "lymphoid-myeloid" multipotentiality of certain leukemic cells.

Cytogenetic studies in 56 cases with Ph1-positive hematologic disorders

Karyotypes were examined in 56 cases of Ph1-positive hematologic disorders based on direct examination of bone marrow material and culture of blood for 24 hr without phytohemagglutinin (PHA). Various banding techniques (Q, followed by R or C, where necessary) were used. The series of patients consisted of 21 females and 35 males with the ages ranging from 3 to 72 years. In three cases, the clinical and hematologic picture at the time of diagnosis and karyotyping was not compatible with chronic myeloid leukemia (CML): 1 case had acute myeloblastic leukemia (AML), another acute lymphoblastic leukemia (ALL) and the third subacute myeloid leucosis. The results are as follows: In three cases (two female, one male), no Ph1 translocation could be demonstrated in any of the metaphases either with Q- or R-banding. In 50 cases (19 female, 31 male), a standard Ph1 translocation, t(9;22)(q34;q11), was observed. In two of these cases, ages 45 and 47, the Ph1 translocation was accompanied by loss of the Y chromosome in all the metaphases examined. Finally, in three cases (all male), variant Ph1-translocations were found: t(7;9)(9;22)(q35?;q31?;q11), and t(1;9)(9;22)(q21;134;q11).

Cytogenetic studies of bone marrow in breast cancer patients after adjuvant chemotherapy

Bone marrow chromosome studies were done on three patients who developed acute nonlymphocytic leukemia 5 to 19 months after completion of adjuvant chemotherapy for breast cancer, and on 17 breast cancer patients without hematologic disease 2 to 30 months after similar adjuvant therapy. Clones of cells with multiple cytogenetic abnormalities were demonstrated in two of the three leukemic patients. No chromosomally abnormal clones or evidence of increased chromosome damage was found in the 17 nonleukemic individuals. Although leukemias induced by chemotherapy, and particularly by alkylating agents, typically show multiple cytogenetic alterations, it appears that patients recently exposed to these agents, but without obvious hematopoietic disorders, do not have a high frequency of aberrant marrow clones. Additional approaches may be needed for early identification of patients at increased risk for chemotherapy-induced leukemia.

C-banding studies in patients with Ph1+ chronic granulocytic leukaemia

The bone marrow chromosomes of 15 patients with Ph1+ chronic granulocytic leukaemia were studied, using both G- and C-banding. In all cases the Ph1 chromosome was formed by the translocation between chromosomes 9 and 22 and the material from chromosome 22 was found to be translocated randomly onto one or other of the pair of 9 chromosomes. Preliminary results suggest that when the translocation was on the 9 chromosome having a smaller C-band, additional abnormalities occurred in blastic transformation, whereas when the 9 chromosome with the larger C-band was involved in the translocation, additional abnormalities were not found in blastic transformation. These observations require confirmation from a larger series. C-banding also showed that there was a greatly increased heteromorphism of the C-band areas of the chromosome pair 9 in this disease, and an increased heteromorphism in the C-bands of chromosome pair 1, when compared with a control group.

New types of unusual and complex Philadelphia chromosome (Ph1) translocations in chronic myeloid leukemia

Nine cases of Philadelphia chromosome-positive chronic myeloid leukemia with an aberrant translocation are reported. In three cases an unusual translocation was found, the recipient chromosome being Nos. 14, 17, and 18, respectively. In six cases the translocation involved a third chromosome in addition to Nos. 9 and 22: there were two cases involving chromosome No. 1, two involving chromosome No. 14, one involving chromosome No. 3, and one involving chromosome No. 12. The clinical significance of the aberrant translocations and the translocation mechanism is discussed.

Chromosomes and causation of human cancer and leukemia: XL. The Ph1 and other translocations in CML

To date, 85 cases with unusual Ph1 translocations have been described and are summarized in the present work. Of the 85 translocations, 41 were simple and 44 complex. Only chromosomes #1, #4, #8, and #20 and the Y have not been found to be involved in simple translocations and #12, #16, #18, #20 and the Y in complex ones. Chromosomes #18, #20, and Y have not been involved to date in either complex or simple Ph1 translocations. Four cases have been reported in whom more tan three chromosomes were involved in the Ph1 translocation and only four cases in whom the #9 was not involved in complex Ph1 translocations. The chromosomal changes, in addition to the Ph1, accompanying unusual Ph1 translocations in CML are not different from those seen in cases with the standard type of Ph1 translocation. Translocations (other than the Ph1) in CML occur in less than 1% of the cases and, to date, have found to involve all the chromosomes except the X and Y. With rare exceptions, in complex Ph1 translocations 1) the distal end of #22 is translocated to a third chromosome (i.e., other than #9), a part of which is translocated to #9, #2) the breaks in the involved chromosomes probably occur concomitantly, and 3) a characteristic PH1 chromosome is present. The survival of patients with CML and unusual or complex Ph1 translocations does not differ significantly from that of patients with the standard Ph1-translocation.

Chromosome studies in preleukemic states. IV. Myeloproliferative versus cytopenic disorders

The prognostic value of marrow chromosome studies was examined in 112 "preleukemic" patients followed for at least one year or until death. Based on recent definitions, 49 patients were classified as myeloproliferative disorders (MPD) (polycythemia vera, myelofibrosis, undifferentiated myeloproliferative disorder, essential thrombocythemia), and 58 as cytopenic states (refractory anemia, pancytopenia). In each group, approximately one-third had a chromosomally-abnormal clone. For MPD, this had little predictive value, but in the cytopenias, 77% with a cytogenetic abnormality developed leukemia versus 39% without. Twelve cytopenic patients had multiple alterations involving more than 2 chromosomes and 11 died within 6 months, 9 with leukemia. Such patients may warrant consideration for aggressive chemotherapy before the appearance of clinical leukemia. Banding studies did not reveal any specific chromosome abnormalities consistently associated with these various preleukemic disorders, or with progression to leukemia, but nonrandom alterations were noted involving chromosomes 1, 5, 7-9, and 20 in the MPD group, and chromosomes 6 and 16 in the cytopenic patients. Correlation of these data with other reports indicates that certain cytogenetic abnormalities involving specific segments of the human genome confer a selective growth advantage on hemic clones which may present clinically as either preleukemia or leukemia.

Three chromosomes' (7;9;22) rearrangement and the origin of the Philadelphia chromosome

A woman with chronic myelocytic leukemia had the Philadelphia chromosome and a complex four-break--three-chromosome rearrangement. The q32 leads to q34 portion of chromosome 9 is translocated to band q22 of chromosome 7, and at the end of this segment is attached the deleted q11 leads to qter portion of chromosome 22. A review of 12 cases of the Philadelphia chromosome originating by the rearrangement of three or more chromosomes reveals that chromosomes 9 and 22 are always involved, while the third chromosome is a different one in each case. We discuss the hypothesis that the 22q segment is always specifically attached to band 9q34 wherever this portion of 9q is transposed.

Atypical chronic myelogenous leukemia with Philadelphia (Ph') chromosome and an additional translocation

A case of chronic myelogenous leukemia in which the disease pursued an atypical course is described. The presence of a previously unreported translocation t(1;20), in addition to a Ph' chromosome t(9;22), is demonstrated, and its possible significance and relationship to the disease are discussed.

Nonrandom chromosome rearrangements in 27 cases of human myeloid leukemia

The R-banding pattern of the chromosomes of 31 patients hospitalized in the Hematologic Clinic for myeloid leukemia were studied before chemotherapy. This analysis permitted identification of one unusual 3-chromosome rearrangement t(3;9;22) in addition to 25 classic forms of (22q-;9q+) translocation accompanied by the specific Ph' chromosome in chronic granulocytic leukemia patients, independent of the blastic course of the disease. During blastic crisis observed in 6 patients, extra 8 and 10 chromosomes, monosomy for chromosome 17, isochromosomes 17q, translocation (12q;13q), and additional Ph' were noted. The nonrandomness of these findings is determined from results published by other authors. Their significance for the cellular phenotype is presently unknown.

A case of chronic myeloid leukemia with a translocation (12;22)(p13;q11)

Chromosomal studies of the bone marrow and cultured peripheral blood cells in a 42-year-old female with the clinical and laboratory features typical for CML revealed a previously undescribed variant translocation involving chromosomes 12 and 22.

Chromosome studies in "preleukemia". III. Myelofibrosis

Cytogenetic studies were done on 18 patients with myelofibrosis or the closely related syndrome, undifferentiated myeloproliferative disorder (MPD). Clones of cells with chromosome abnormalities were demonstrated in the blood of eight individuals, including two with a history of radiation therapy and two with "acute myelofibrosis". Trisomy 8 was present in the latter two patients, but otherwise, there was no consistent cytogenetic pattern or correlation with specific hematologic findings. Sixteen of these patients have been followed for more than 1 year or until death; none has progressed to leukemia. The results indicate that chromosome abnormalities are relatively common in this disorder, but as with polycythemia vera, and unlike some other "preleukemic" states, the aberrant clones in myelofibrosis do not appear to indicate that clinical leukemia is imminent.

T cell variant of chronic lymphocytic leukaemia with chromosome abnormality and defective response to mitogens

Lymphocytes from a patient with chronic lymphocytic leukaemia, in whom therapy was ineffective, were defined as thymus-derived (T) cells by membrane markers (sheep erythrocyte rosettes, complement rosettes, surface immunoglobulin). The lymphocytes responded weakly to two mitogens, phytohaemagglutinin and the calcium ionophore A23187, but not to concanavalin A. Cytogenetic studies of leukaemic cells from unstimulated and mitogen-stimulated cultures revealed an abnormal karyotype with 45 chromosomes and multiple rearrangements. The T cell variant of classical chronic lymphocytic leukaemia is relatively rare; additional reports are needed to determine if the clinical course is typically less benign than in the common B cell variety, or whether this patient simply represented a late, unresponsive phase of the disease.

Non-random karyotypic evolution in chronic myeloid leukemia

The chromosome banding pattern was analyzed in bone-marrow cells and/or spleen cells of 10 patients in the blastic phase of chronic myeloid leukemia (CML). It was obvious from the karyotype analysis that the chromosome aberrations occurring addition to the Philadelphia chromosome (Ph1) were strictly non-random. An extra Ph1, trisomy 8 and/or trisomy for the long arm of chromosome 17 were observed in all cases. This consistent pattern of chromosome involvement in CML was confirmed in 57 cases from the literature studied with banding techniques. In 88% of the total number of cases with further changes at least one of the three main chromosomal aberrations was found ("major route" of karyotypic evolution).

A new translocation in chronic myelogenous leukemia

A reciprocal translocation involving chromosomes Nos. 3 and 22 has been found in a patient with seemingly Ph-negative chronic myelogenous leukemia (CML). G-band analysis revealed, that deletion in No. 22 occurred at the same point, as in the typical cases of the disease. It was concluded, that breakage in No. 22 at a specific site with spatial disjunction of the resulting segments might be the crucial cytogenetic event in the genesis of CML, the Philadelphia chromosome not being an obligatory result of the rearrangement.