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The t(8;21) translocation breakpoint, which is observed in acute myeloid leukemia (AML), has recently been cloned and a fusion transcript identified. We have now designed primer sets capable of amplifying the breakpoint junction of the fusion transcript by the reverse transcription-polymerase chain reaction (RT-PCR). Primer set 821U/821D1 amplified a 200-bp DNA fragment, and primer set 821U/821D2 amplified a 1.2-kb DNA fragment in all t(8;21)-positive AML tested. Sequence analysis of the amplified DNA fragments demonstrated that all fusion transcripts were fused at exactly the same site, indicating that this translocation breakpoint occurs within a single intron of the AML1 and ETO genes. Forty-five cycles of RT-PCR were used to detect residual t(8;21)-positive leukemia cells in three patients who had been in complete remission for 1, 3 and 5 years. Minimal residual disease was found in all three samples. Northern blot analysis demonstrated that two fusion transcripts of 7 and 10 kb were expressed in the t(8;21)-positive AML and that the ETO gene is not normally expressed in the hematopoietic system. Expression of a normal 5.5-kb ETO mRNA was found in the lung. From these results we concluded that expression of the ETO gene in t(8;21)-positive AML was activated as a result of the translocation.

We have developed a restriction map of the chromosome 21 breakpoint region involved in t(8;21)(q22;q22.3) acute myelogenous leukemia (AML) and have isolated a genomic junction clone containing chromosome 8 and 21 material. Using probes from these regions, rearrangements have been identified in each of nine cases of t(8;21) AML examined. In addition, we have isolated cDNA clones from a t(8;21) AML cDNA library that contain fused sequences from chromosome 8 and 21. The chromosome 8 component, referred to as ETO (for eight twenty-one), is encoded over a large genomic region, as suggested by the analysis of corresponding yeast artificial chromosomes (YACs). The DNA sequence of the chromosome 21 portion of the fusion transcript is derived from the normal AML1 gene. A striking similarity (67% identity over 387 bp, with a corresponding 69% amino acid identity) was detected between AML1 and the Drosophila segmentation gene, runt. The critical consequence of the translocation is the juxtaposition of 5' sequences of AML1 to 3' sequences of ETO, oriented telomere to centromere on the der(8) chromosome.

The retinoblastoma (RB) protein levels in blast-enriched mononuclear fractions from the peripheral blood of 33 newly diagnosed patients with acute myelogenous leukemia were studied. Ten patients who had previously been treated were also analyzed, nine of whom had achieved prior complete remission. Low RB protein expression was found in 13 of 43 (30%) of the acute myelogenous leukemia patients as determined by Western blotting and immunochemical analysis. Of particular interest among the 20 newly diagnosed patients treated with the same therapeutic regimen, the median survival was 39 days for those with low RB protein expression compared to 333 days for those with high levels of RB protein expression in their leukemic cells (P less than or equal to 0.02). This preliminary study suggests that decreases of RB protein expression in peripheral blood of myeloid leukemic cells occur frequently and may be associated with shortened survival of acute myelogenous leukemia patients.

Bone marrow samples collected from acute myeloblastic leukemia (AML) patients in complete clinical and hematological remission were studied for the persistence of cytogenetic abnormalities. AML patients from the three favorable cytogenetic categories [inv 16, t(8;21) and t(15;17)] and patients from the unfavorable cytogenetic categories (+8, -5, -7 and Philadelphia-positive) were studied. Seventy-one patients had evaluable metaphase spreads in remission marrows and 20 (28%) had one or more abnormal metaphases identical to that present in the pretreatment marrow. All 20 of these patients relapsed within 78 weeks, thus there were no false positive studies. Fifty-one patients had only diploid metaphases in their complete remission marrow, 25 relapsed, and 21 remained in continuous complete remission. Thus there was a 49% false negative rate of this study. These data indicate that the failure to detect residual chromosomally abnormal cells in the bone marrow does not guarantee continuous complete remission. Cytogenetic study was most useful in the favorable cytogenetic groups and least useful in the unfavorable groups. The persistence of normal metaphases in pretreatment marrows did not affect outcome or risk of recurrence. Twenty-five of 34 evaluable patients who relapsed after remission had either the identical cytogenetic abnormality present in the pretreatment marrow or showed the identical abnormality with additional chromosomal changes. Thus study indicates that cytogenetic examinations of complete remission bone marrow samples in patients with AML provides an objective method for detecting residual leukemia, and identifies patients with a potential for prolonged disease-free survival.

Evidence suggests that prognosis in patients with myelodysplastic syndromes (MDS) or acute myelogenous leukemia (AML) depends more on karyotype than on formal classification as either MDS or AML according to the French-American-British (FAB) system. We provide further evidence of overlap between these two entities, reporting 4 patients who presented with either inv(16) (p13q22), del(16) (q22), or t(8;21) despite an FAB diagnosis of MDS rather than the diagnosis of AML with which these abnormalities are generally associated. In 3 patients, disease was relatively long-standing (3-10 months) prior to diagnosis, suggesting that the association between MDS and these cytogenetic abnormalities may not merely reflect a transient phenomenon. Two patients with inv(16) and the MDS subtype refractory anemia with excess blasts in transformation (RAEB-t) received AML-type chemotherapy as did a patient with t(8;21) and RAEB-t. All entered CR paralleling the high CR rate seen in patients with AML and these abnormalities. Our data support the concept that MDS and AML may be different manifestations of the same disease.

An 8;20 chromosomal translocation was observed in the leukemia cells of a 3-year-old girl. To our knowledge, this is the first report of this translocation in de novo acute leukemia. This chromosomal defect was present in the leukemia cells at diagnosis and also at relapse, but remission bone marrow cells had the 46,XX karyotype. By morphologic and cytochemical criteria the leukemia was myeloid but these features were more lymphoid when the leukemia recurred. However, the immunophenotype was consistent with myeloid leukemia and did not change at relapse. No evidence for either immunoglobulin or TCR gene rearrangement was observed.

Three previous investigations have reported a relationship between clonal chromosome abnormalities in marrow of patients with acute nonlymphocytic leukemia and employment in occupations involving mutagenic chemicals, but the effects of other exposures were not described. Environmental exposure profiles, gathered by questionnaire, were therefore compared using a case-control study design in 235 newly diagnosed patients with acute nonlymphocytic leukemia: 126 with abnormal and 109 with normal karyotypes. The univariate odds ratio for occupation at diagnosis was 4.6, which, when adjusted for demographic and other exposures by logistic regression, was reduced to 2.5 (95% confidence interval, 0.5 to 12.8). Adjusted point estimates for other exposures were 4.3 (1.4 to 13.3) for prior cytotoxic therapy, 1.7 (0.9 to 3.1) for cigarette smoking, and 1.9 (1.0 to 3.4) for alcohol use. Dose-response relationships were present for both tobacco and alcohol consumption. Associations between specific abnormalities (+8, -7I-7q, [corrected] inv16, t[8;21]) and certain exposures were also present. These results suggest that life-style exposures may be associated with cytogenetic lesions in persons with acute nonlymphocytic leukemia.

Thirty-four adult patients were seen at the University of Texas M. D. Anderson Hospital and Tumor Institute at Houston, Texas between 1969 and 1980 with acute leukemia (AL) and a deleted G-group chromosome that was shown by Giemsa banding to be a Philadelphia (Ph1) chromosome t(9;22) in 21 patients. Fourteen had the Ph1 chromosome as the sole abnormality, 12 had the Ph1 chromosome and loss of one chromosome of the C-group (identified by Giemsa banding analysis as number 7 in eight patients), while eight had the Ph1 chromosome and other changes. These three groups were similar in sex, age distribution and hematologic parameters. The median age of 40 was lower than usually seen in AL. The distribution of the morphologic subtypes was similar to that seen at this institution, with 50% being acute myeloblastic, 12% acute myelomonocytic, 20% lymphoblastic and 18% acute undifferentiated. The complete remission rate with chemotherapy was low: 25% in the Ph1 +/- 7, 50% in the Ph1 +/other group and 43% in the Ph1 +/other group. Median survival time was 8 months for the Ph1 +/- 7 group, 5.5 months for the Ph1 +/other group and 9.0 months for the Ph1 +/alone group. These patients with Ph1 + AL had higher white blood cell counts, increased extramedullary disease and poorer responses to therapy than usual for patients with AL. The deletion of chromosome 7 and the acquisition of the Ph1 chromosome identifies a group of patients with characteristics similar to all the patients with Ph1 + AL but a poor response to therapy and short remission duration.

Ten patients with acute myelomonocytic leukemia (AMML) and inversion of chromosome 16 who had CNS involvement were identified at M.D. Anderson Hospital between January 1972 and December 1984. The nervous system signs and symptoms were evaluated in detail. CT scans, CSF cytologies, and treatment modalities were reviewed. Two patients underwent biopsies of lesions that proved to be granulocytic sarcomas. AMML with inversion 16 carries a much higher (33%) incidence of CNS involvement in the form of leptomeningeal metastasis and/or granulocytic sarcoma than all other acute nonlymphocytic leukemias (5%). The reason for this appears to be related to the chromosomal aberration and not to prolonged survival.

Cytogenetic studies with Giemsa banding were performed on the bone marrow cells of 384 patients with acute myelogenous leukemia treated between 1975 and 1983. An abnormal karyotype was detected in 54% of patients, being present in 100% of metaphases (AA) in 31% and only a proportion of cells (AN) in 22%. Specific translocations or other abnormalities were noted in 22% of patients, the most common of which were t(8;21) (q22;q22) in 7%, t(15;17) (q22;q21) and inv (16) (p13q22) in 5.5%, t(9;22) (q34;q11) in 3% and abnormalities of 11q23 in 1.3%. Loss of the Y chromosome was noted in 21 patients, associated with t(8;21) in 11 patients and the sole abnormality in eight patients (45, X, -Y). Most (66%) of the other abnormalities involved addition of chromosome 8 or loss or deletion of 5 or 7 (+8, -5 or -7, 5q- or 7q- group). The remaining patients had miscellaneous abnormalities (MA). A marked assymetry was noted in the distribution of important clinical prognostic variables such as age, sex, history of an antecedent hematologic disorder and presence of Auer rods within the various cytogenetic categories. The specific translocation/abnormalities were more common in younger patients (p less than 0.01). Analysis of response, remission duration and survival demonstrated that inv 16 and t(8;21) were favorable prognostic categories; diploid, t(15;17) and 45,X,-Y had intermediate prognosis, and all other categories were unfavorable prognostic groups. The response rate and survival for diploid patients (NN) was superior to patients with abnormalities. No difference in response rate, CR duration or survival was noted between the AA and AN groups. A prognostic classification according to cytogenetic category based on clinical associations is proposed which will be tested prospectively in subsequent studies.

Forty-three patients with acute myelogenous leukemia (AML) and a translocation 8;21 were reviewed. The patients' median age was 30 years, and 62% were men. Twenty-three patients (53%) had loss of a sex chromosome and ten (23%) had other chromosomal abnormalities in addition to the 8;21 translocation. Complete remission (CR) with induction chemotherapy was achieved in 40 patients (93%). The median CR duration was 18 months (range, 1 to 137+ months). Median survival time was 17 months (range, 0.5 to 138+ months) with a 3-year survival rate of 31%. Twenty-three patients (53%) relapsed between 1 and 58 months after entering remission with reinduction therapy resulting in 8 CRs (35%). Thirteen characteristics were examined for an effect on survival. The most striking finding was a significant association between elevated absolute granulocyte count and poor survival (P = .002). WBC count greater than 10,000/microL was also associated with shorter survival (P = .05). Patient age, albumin level, and platelet count showed trends for survival association. Although patients with AML and t(8;21) are regarded as a favorable group with respect to survival, we found a subset of patients who do very poorly. Intensive or more investigational approaches in first remission should be considered for these patients.

Of 476 patients with multiple myeloma treated during a 9-year period, 11 developed acute myelogenous leukemia or sideroblastic anemia. In all, the myeloma was in remission from chemotherapy with melphalan-prednisone combinations that had been continued for a median duration of 3 years. The incidence of acute leukemia or sideroblastic anemia was about 100 times higher than found in normal individuals of the same age. In all patients studied, major cytogenetic abnormalities were present, with hypodiploidy and evidence of chromosomal damage being noted most frequently. The frequency and nature of the chromosome changes were attributed to effects resulting from the prolonged drug therapy. These findings supported the long-term follow-up of selected patients with myeloma without any chemotherapy when marked degrees of remission followed the initial treatment courses.

This study demonstrates that a differentiation-specific gene, the myeloperoxidase (MPO) gene, is translocated in a patient with acute promyelocytic leukemia (APL). The MPO gene recently has been mapped to chromosome #17, close to the breakpoint involved in the t(15;17) commonly seen in APL. By in situ hybridization, we showed that this gene was translocated from chromosome #17 to #15 in an APL patient. Although the significance of this translocation remains unclear, MPO is known to be highly expressed in APL. The causal relationship between the high expression and translocation of this gene requires further investigation.

The T-cell receptor gamma chain (TcR gamma) gene is rearranged in early T-cell differentiation. However, rearrangement of the TcR gamma gene is not specific for T lineage since it has also been noted in B-cell neoplasia. TcR beta gene rearrangement and heavy chain immunoglobulin gene rearrangement have also been reported in acute myelogenous leukemia (AML). Because of the previous reports of lineage heterogeneity at the molecular level, we analyzed seven patients who met the standard criteria for AML by Southern blot hybridization with a TcR gamma gene probe, a TcR beta gene probe, and an immunoglobulin heavy chain JH gene probe. In two samples, the TcR gamma gene was rearranged. One of these two samples also had rearrangement of the immunoglobulin JH gene. None of the seven samples showed TcR beta gene rearrangement. The two samples with TcR gamma gene rearrangement also showed 25% and 80% of terminal deoxynucleotidyl transferase (TdT) positivity, respectively. Both samples expressed myeloid lineage-associated antigens without any lymphoid lineage-associated antigens. Our studies indicate that TcR gamma gene rearrangement is not specific for lymphoid lineage and the presence of TcR gamma and immunoglobulin JH gene rearrangements without expression of lymphoid lineage-associated markers supports the concept that there is lymphoid lineage prematurity in AML.

The human myeloperoxidase (MPO) gene has recently been cloned in our laboratory. Southern blot hybridization of our MPO cDNA to DNA from a somatic cell hybrid clone panel revealed that the MPO cosegregated with human chromosome 17. In situ hybridization mapped the MPO gene to chromosome 17q22-24. Although this location is close to the translocation breakpoint which occurs in acute promyelocytic leukemia (APL), t(15;17)(q22;q21-22), Southern blot hybridization with different restriction-digested genomic DNA samples from four APL patients did not reveal MPO gene rearrangement. However, RNA dot-blot hybridization showed that APL patients with the translocation expressed high levels of MPO mRNA. This observation raises the possibility that the high levels of MPO gene expression in APL could be due to the arrest of leukemic cells at a specific stage of differentiation or a consequence of the translocation.

An analysis was conducted of clinical and laboratory variables associated with response to remission induction therapy and remission duration in 440 patients with acute myelogenous leukemia treated between 1975 and 1983. The complete remission rate was 259/440 (59%). Specific cytogenetic abnormalities such as t(8;21), t(15;17), and inv16 were found to be favorable for response to therapy and/or remission duration, whereas those with a normal (diploid) karyotype had an intermediate prognosis. All other karyotypic abnormalities were associated with lower response rates and short complete remission durations. The karyotypes were classified as favorable, intermediate, and unfavorable groups for response and remission duration after allowing for all the other observed clinical and laboratory values related to prognosis. The cytogenetic classification was prospectively validated in an independent test group of 130 patients treated between 1983 and 1986 and showed a consistent relationship to response and remission duration. Logistic regression and proportional hazard models developed from the initial 440 patients were prospectively evaluated in the test group of 130 patients. Clear stratifications of patients into good, intermediate, and poor risk groups were obtained in the prospective tests. The karyotype of the leukemia cells is an independent prognostic variable for response and remission duration in acute myelogenous leukemia.

Six cases of acute leukemia that underwent lineage switch from acute lymphocytic leukemia to acute myelogenous leukemia are reported. The mean age of the patients was 24 years, time to conversion was 36 months, and survival after conversion was only 3 months. Of the three cases which showed abnormal metaphases at both diagnosis and conversion, two (cases 2, 5) showed related cytogenetic abnormalities, and the third showed (case 3) independent chromosomal changes. Molecular analysis for immunoglobulin heavy chain and T-cell receptor beta chain genes showed that five of the six cases had rearrangement of at least one of these lymphoid associated genes at conversion to acute myelogenous leukemia. The single case (case 3) in which there were no lymphoid gene rearrangements at conversion was also the only case in which independent karyotypic abnormalities at diagnosis and conversion were demonstrated. Our findings suggest that lineage switch can represent either relapse of the original clone with heterogeneity at the molecular level or the emergence of a second new leukemic clone without molecular heterogeneity.

A technique for cloning myeloblastic leukemic cells in semi-solid agar, after prior PHA stimulation, was studied in all phases of chronic myeloid leukemia. Phytohemagglutinin responsive cells were found in blast crisis and accelerated phase. In a small number of patients in the benign phase of their disease, colony growth with PHA was detected. A group of patients with early acute leukemia was also examined by this technique. The incidence of PHA colonies appeared to correlate with the progression of the disease. The potential application of this assay for early detection of leukemic clones and possible prediction of the rapidity of progression of the leukemic process is discussed.

Cytogenetic studies were performed in 546 patients with acute leukemia between 1968 and 1975. Two hundred thirty-four patients were aneuploid (42.9%), and 312 patients were diploid (57.1%). Among these, 32 patients were found to exhibit similar chromosomal alterations that appeared to involve specifically chromosomes 8 and 21. Banding studies in at least 15 of these patients confirmed the presence of a translocation between these two chromosomes. The cytogenetic findings were correlated with the hematologic and clinical data. It was found that each of these individuals had a typical picture of acute granulocytic leukemia with Auer rod-positive and peroxidase-positive cells. Ultrastructurally, the patients in this group also consistently demonstrated the presence of a nuclear bleb that has been positively associated with aneuploidy in acute leukemia. Clinically, they seemed to respond better to therapy than other adult patients with acute granulocytic leukemia. It is proposed that the 8/21 translocation acute leukemia represents a definite subgroup within the general category of acute granulocytic leukemia, with an incidence of approximately 7.3%.

Using flow cytometric techniques, we determined DNA ploidy levels in the bone marrow of 318 successive adult patients with newly diagnosed acute leukemia. Overall, 26% exhibited DNA stem line abnormalities, usually with a 10%-15% DNA excess, regardless of morphologic diagnosis. DNA aneuploidy was seen most frequently in patients with a hyperdiploid chromosome number and karyotype instability (50%), but was also present in a third of patients with chromosomal translocations and in 20% of patients with a normal diploid karyotype. Thus, among 73 patients with DNA aneuploidy, quantitatively concordant karyotype abnormalities were observed in almost 40% of patients; the discrepancy between DNA content and chromosome number in the remaining patients may reflect differences in the cell cycle position of target cells in G1/0 phase or mitosis, respectively. Cytogenetics affected treatment outcome in acute myelogenous leukemia (AML) with more favorable short- and long-term prognosis among patients with translocations compared with those with numeric abnormalities. The presence of an abnormal DNA stem line, among AML patients with translocations, identified a favorable subgroup with significantly longer remission duration and survival (25 and 26 months versus 18 and 13 months, respectively). In addition, the prognostic implications of DNA aneuploidy in AML were age-dependent, in that favorable effects among patients with translocations and unfavorable effects among those with numeric abnormalities or diploid karyotypes were most obvious in young and not in older patients (greater than or equal to 40 years). In adults with ALL, DNA aneuploidy was associated with shorter survival (15 versus 39 months in the diploid group), an observation that is distinctly at variance with recent findings in childhood ALL. Our results indicated that DNA flow cytometry was complementary to standard cytogenetics for the detection of genomic abnormalities; and DNA aneuploidy emerged, like in children but not in adults with ALL, as a new favorable prognostic feature in a subgroup of adults with AML, the biologic basis of which remains to be determined.

Twenty-six patients with inv(16)(p13q22) or del(16)(q22) in association with acute myelomonocytic leukemia (AMML-M4, FAB classification), and abnormal marrow eosinophils have been treated at this institute. Initial bone marrow eosinophilia (greater than or equal to 4%) was observed in 22 of 26 patients (85%), and abnormal eosinophil morphology, characterized by immature cells with some interspersed basophilic granules, was evident in 26 of 26 (100%). Giemsa-banded chromosome analysis performed in all patients revealed 16 cases with inv(16)(p13q22) alone, and ten cases with additional chromosome changes. Twenty-five patients received combination induction chemotherapy, and 23 (92%) achieved complete remission (CR). The median duration of remission was 18 months (range, six to 72 + months), and the median duration of survival was 34 months (range, 0.5 to 133 months). Nine patients (35%) relapsed in the CNS at a median time of 19 months (range, six to 133 months) from first marrow CR. All patients had leptomeningeal disease, and in addition, six of nine (66%) demonstrated two or more enhancing lesions on computed tomography brain scan, consistent with intracerebral myeloblastomas. Review of 384 Giemsa-banded patients with acute myeloid leukemia revealed no other morphologic or cytogenetic subgroup with either an equivalent incidence of CNS leukemia or documented intracerebral myeloblastomas. This series of inv(16)(p13q22)/del(16)(q22) AMML reports a favorable prognosis for such patients and associates a specific clonal cytogenetic subgroup of acute leukemia with a distinct propensity for CNS relapse, manifesting as leptomeningeal disease and intracerebral myeloblastomas.

Patients with myelodysplastic syndrome (MDS) and patients with acute myelogenous leukemia (AML) share certain specific karyotypes. Therefore, we compared the relative importance of karyotype and morphology (MDS vs. AML) in determining survival in these patients. We analyzed 768 patients with a banded karyotype who presented as either MDS or AML. Patients with "unfavorable" karyotypes had similarly short survivals regardless of whether they were classified as refractory anemia with excess blasts (RAEB), refractory anemia with excess blasts in transformation (RAEBT), or AML. Patients with diploid karyotypes survived significantly longer, again with relatively minor differences between patients with RAEB, RAEBT, and AML. We conclude that classification of patients with excess myeloblasts in the marrow might more appropriately be based on cytogenetics than on the distinction between MDS and AML.

The leukemia from which the human cell line HL-60 was derived was classified in 1976 as acute progranulocytic leukemia (APL), although it was recognized to show a number of atypical features. In the ensuing 10 years, the concept of APL and its integral association with t(15;17) has evolved, and the concept of APL as a morphologically recognizable entity has become embodied in the term French-American-British classification M3 (FAB-M3). It is now recognized that not every case of leukemia with a high proportion of progranulocytes can be classified as FAB-M3. We reviewed the light and ultrastructural morphology of the original diagnostic material from this case, and we report that the leukemia from which HL-60 was derived does not conform to the currently recognized entity of FAB-M3 and is more appropriately classified as an acute myeloblastic leukemia with maturation, FAB-M2.

Sixty patients with acute promyelocytic leukemia were treated between 1973 and 1984. The overall median survival was 16 months with a five-year survival rate of 31 percent. The complete remission rate was 53 percent and was similar whether they received amsacrine- or anthracycline-based regimens (60 percent versus 51 percent). The median remission duration was 29 months. At five years, 43 percent of patients with responses to treatment had continuous remission and 57 percent were alive. Salvage therapy produced remissions in 53 percent of patients during first relapse, with two long-term survivors after further consolidation with bone marrow transplantation. Early fatal hemorrhage associated with disseminated intravascular coagulopathy during induction therapy occurred in 16 patients (26 percent). Multivariate analysis of the pretreatment patient characteristics significantly associated with an increased risk of fatal hemorrhage identified four that have primary prognostic importance: thrombocytopenia, elevated absolute blast and promyelocyte counts, old age, and anemia. Patients having up to two unfavorable features had a low risk of fatal hemorrhage compared with those who had more than two (5 percent versus 58 percent; p less than 0.0001). Overall, patients who received heparin had a lower incidence of fatal hemorrhage than those who did not (19 percent versus 32 percent). Heparin therapy was not beneficial to those at low risk but was associated with a trend towards decreased hemorrhagic deaths among high-risk patients (45 percent versus 67 percent). Cytogenetic studies demonstrated the characteristic 15;17 translocation in 73 percent of patients with analyzable metaphases, whereas 12 percent had other karyotypic abnormalities. Remission induction was often associated with a gradual atypical morphologic evolution into remission without intermediate hypoplasia with the interim marrows showing a high proportion of blasts. It is concluded that acute promyelocytic leukemia is a unique disease with a high potential for cure. Knowledge of its prognosis using present frontline and salvage therapy, of the factors related to fatal hemorrhage, and of the unusual patient marrow profiles during remission induction may improve the therapeutic approach.

Thirteen male patients with acute myelogenous leukemia who, on bone marrow chromosome analysis, were missing all or part of the Y chromosome were treated at this institution between 1975 and 1983. Giemsa-banding techniques were performed in 12 cases. Twelve showed -Y in at least 80% of bone marrow metaphases, and one patient had 25% 46,XYqh-. The loss of the Y chromosome was the sole karyotypic abnormality in nine patients, and the remaining four had additional chromosome changes. The peripheral blood lymphocytes were diploid in all except three cases, where no mitotic cells were recovered. The median age was 55 years, eight patients had acute myelogenous leukemia (M2) and five acute myelomonocytic leukemia (M4). Six patients (46%) had an antecedent hematologic disorder. Eleven patients received standard induction combination chemotherapy. Complete remission was achieved in seven patients (63%). Remission bone marrow chromosome analysis showed 100% 46,XY in all seven cases. The median durations of complete remission and survival were 10 months and 12 months, respectively. The review suggests that -Y is a consistent, although uncommon, chromosome marker in acute myelogenous leukemia, associated with an aggressive clinical course and intermediate prognosis.