Chromosomes in Hodgkin's disease--analysis of involved lymph nodes.

Chromosome studies carried out using lymph nodes of 47 patients with Hodgkin's disease gave analyzable metaphases in 22 patients of which 16 (72.7%) showed chromosome abnormalities. The modal chromosome number ranged from near-diploidy to near-tetraploidy. Chromosomes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 21 and 22 were involved in trisomy and tetrasomy whereas chromosome 17 was involved in monosomy. Structural abnormalities like deletions of chromosomes 1(p13), 6(q24) and addition of chromatin material to chromosomes 11(q13) and 14(q32) were also detected. The involvement of chromosomes 2, 5, 12, 18 and 21 in numerical abnormalities, and chromosome 14(14q+) in structural aberrations was found to be more frequent in Hodgkin's disease. No clinical correlation could be defined between the various chromosome abnormalities and prognosis of these patients.     

Value of comparative genomic hybridization and fluorescence in situ hybridization for molecular diagnostics in multiple myeloma

Chromosomal abnormalities, such as 13q deletions, are emerging as important prognostic factors in multiple myeloma. Fluorescence in situ hybridization (FISH) using specific DNA probes is the technique most widely used for the determination of genomic aberrations in this disease. The utility of comparative genomic hybridization (CGH) for molecular diagnostics in plasma cell malignancies has not been systematically analysed. We investigated tumour samples of patients with multiple myeloma (n = 43) or plasma cell leukaemia (n = 3) using CGH and FISH with five DNA probes localized to chromosome bands 1p22, 6q21, 11q22-q23, 13q14 and 17p13. By CGH, the most frequent genomic changes were gains on chromosomes 1q, 9q and 11q, as well as losses on chromosomes 13q, 6q, Xp and Xq. By FISH, trisomy 11q was identified at a similar frequency to the 13q deletion (42%). Compared with FISH data, the sensitivity of CGH was 80.7% and the specificity was 97.5%. Thirty-two aberrations found by FISH were not identified by CGH, mostly as a result of the proportion of cells carrying the respective aberrations, or because of the limited spatial resolution of CGH. Our data indicate that, for clinical molecular diagnostics in multiple myeloma, FISH with a disease-specific DNA probe set is superior to CGH analysis.     

Secondary Abnormalities of Chromosome 6q in B-Cell Chronic Lymphocytic Leukemia: A Sequential Study of Karyotypic Instability in 51 Patients

Although karyotypic abnormalities are well documented in B-cell chronic lymphocytic leukemia (B-CLL), few sequential cytogenetic studies have been done. In this study, peripheral blood lymphocytes from fifty-one patients with B-CLL were sequentially karyotyped over a mean interval of 13.8 months (range, one to 51 months). Cytogenetic clones were detected in 33/51 patients (66%) on initial study, including 17 patients with structural abnormalities of chromosome 13q14, and three patients with trisomy 12. Karyotypic evolution was documented in 22/51 patients (43%). The most common secondarily acquired chromosome aberrations were structural abnormalities of the long arm of chromosome 6 involving the region of 6q21-q24 (six patients). Four patients each had acquired structural abnormalities of 1q, 3p, 12q, and 13q. Disease progression, as measured by advance in Rai stage or death from the disease, was observed more often in the clonal evolution group than in the karyotypically stable group (11/22 vs. 5/29; P = 0.017). Patients with secondary abnormalities of 6q had a significantly decreased progression-free survival interval compared with other patients in the study (P = .023). The authors conclude that clonal karyotypic evolution is common in B-CLL, and that clonal evolution correlates with clinical disease progression. Furthermore, the poor outcomes previously attributed to CLL with 6q abnormalities may be related to the clonal acquisition of these abnormalities over time. Future studies should focus on the relevant genetic events underlying the clinical progression observed with karyotypic evolution of B-CLL. Am. J. Hematol. 59:223–229, 1998. © 1998 Wiley-Liss, Inc.     

Chromosome aberrations in de novo acute myeloid leukemia patients in Kuwait

Cytogenetic analysis was successfully performed at the time of diagnosis in 45 patients with de novo acute myeloid leukemia, including 10 children and 35 adults. In approximately 73% of AML patients (35 patients) clonal chromosome abnormalities were detected at the time of diagnosis. Twelve patients (22.8%) had apparently normal karyotypes. Recurring aberrations found in 22 of patients with abnormal karyotypes included t(15;17)(q22;q11), t(8;21)(q22;q22), inv(16)(p13q22), trisomy 8, monosomy 7 and del(5q). The highest frequency of chromosome changes was observed in AML-M3. The occurrence of the classical cytogenetic abnormalities was not a ubiquitous phenomenon. In 11 patients previously not described miscellaneous clonal chromosomal abnormalities were detected. Clonal chromosomal abnormalities detected in AML have shown correlations between specific recurrent chromosomal abnormalities and clinico-biological characteristics of the patients, therefore have been repeatedly shown to constitute markers of diagnostic and prognostic significance. Moreover, ongoing cytogenetic analysis can identify new nonrandom chromosome aberrations in AML and contribute to the identification of novel genes involved in the development of cancer, which can lead to better understanding of the disease pathogenesis.     

Different genetic pathways in leukemogenesis for patients presenting with therapy-related myelodysplasia and therapy-related acute myeloid leukemia

Development of myelodysplasia (MDS) with subsequent progression to acute myeloid leukemia (AML) is an example of the multistep process of malignant transformation in which each step often relates to genetic abnormalities that can be directly seen as chromosomal aberrations. Therapy-related MDS and AML (t-MDS and t-AML) may serve as an ideal model for a study of the genetic evolution of MDS and AML because chromosomal abnormalities are observed in most cases and because the disease is often diagnosed early due to a close patient follow-up. The cytogenetic characteristics at diagnosis were studied in 137 consecutive cases of t-MDS and t-AML, including 22 new cases, and correlated with the clinical characteristics and the course of the disease. Balanced translocations to chromosome bands 11q23 and 21q22 represent primary steps in pathways leading directly to overt t-AML. Specific chromosomal deletions or losses, on the other hand, represent primary or secondary events in alternative pathways leading to t-MDS with potential for subsequent transformation to overt t-AML. Loss of a whole chromosome 7 (-7) or deletion of its long arm (7q-) and deletion of the long arm of a chromosome 5 (5q-) were the most frequent primary abnormalities significantly related to t-MDS. Loss of a whole chromosome 5 (-5) was also a primary event, but surprisingly, was observed equally in t-MDS and in t-AML. Deletion of chromosome 13, including bands q13q14, was another less common primary aberration of t- MDS. Except for -7 and del(13q), these primary aberrations were most often observed together with secondary abnormalities. These included balanced aberrations involving band 3q26 and various deletions of chromosome 3, a gain of a whole chromosome 8, deletions of the short arm or loss of chromosomes 12 and 17, loss of a whole chromosome 18, and deletions of the short arm of chromosome 21. Deletions or loss or chromosomes 5 and 7 were significantly associated with previous therapy with alkylating agents (P = .002), and balanced translocations to chromosome bands 3q26, 11q23, and 21q22 were significantly associated with previous therapy with drugs targeting DNA-topoisomerase II (P < .00005). Other characteristic aberrations were not related to any specific type of therapy. The molecular changes believed to contribute to the development of t-MDS and t-AML have been identified for many of these chromosomal abnormalities.     

Chromosome aberrations are restricted to the CD56+, CD3− tumour cell population in natural killer cell lymphomas: a combined immunophenotyping and FISH study

Natural killer (NK) cell lymphomas are a newly recognized entity of non-Hodgkin's lymphoma with a highly aggressive clinical course and strong association with Epstein-Barr virus (EBV) infection. Although no recurrent chromosome aberrations have been identified in NK-cell lymphoma, deletions of 6q and trisomy 7 have been described repeatedly in this type of lymphoma. In this study we attempted to determine the immunophenotypes of tumour cells with certain chromosome aberrations, i.e. deletions of 6q and trisomy 7, in three cases of NK cell lymphomas by means of combined immunophenotyping and fluorescence in situ hybridization (FISH). In all three cases clonal chromosome aberrations were detected only in CD56+ cells but not in CD3+ or CD5+ cells. However, not all CD56+ cells were shown to contain these chromosome aberrations. Double immunophenotyping combined with FISH confirmed that the chromosome aberrations occurred only in CD56+CD3- cells. This study indicates that chromosome aberrations in NK-cell lymphomas are restricted to the CD56+, CD3- and CD5- cell population and that NK-cell lymphomas are indeed derived from mature true NK cells and not from T lymphocytes.     

Twenty-three cases of acute lymphoblastic leukemia with translocation t(4;11)(q21;q23): the implication of additional chromosomal aberrations

The translocation t(4;11)(q21;q23) is one of the most common specific chromosomal aberrations in acute lymphoblastic leukemia (ALL), occurring in 2% of childhood and in 5–6% of adult cases. Especially in adults, the t(4;11) is associated with a poor prognosis. In order to determine the significance of clonal chromosome aberrations that occur in addition to t(4;11), we studied the karyotypes and clinical courses of 23 patients with acute lymphoblastic leukemia and a translocation t(4;11)(q21;q23). Additional clonal chromosome aberrations were found in ten patients. An isochromosome i(7)(q10) and a trisomy 6 were observed most frequently as secondary anomalies. Clonal evolution was detected in four of six patients analyzed at diagnosis as well as at relapse. With treatment carried out according to modern risk-adapted therapy protocols, no difference in outcome was observed between patients with clonal chromosome aberrations in addition to t(4;11) at diagnosis and those without.     

Multipoint interphase FISH analysis of chromosome 3 abnormalities in 28 childhood AML patients

We detected non-random 3p losses and 3q gains on well-determined regions in both murine and human tumors using a microcell hybrid-based model system called 'elimination test'. We suggest that these are general malignancy-associated aberrations not necessarily linked to a particular tissue of origin. To examine chromosome 3 abnormalities, in 28 childhood acute myeloid leukemia bone marrow samples, we performed interphase multipoint-fluorescence in situ hybridization using 84 chromosome 3-specific probes and detected clonal chromosome 3 aberrations in nine cases, which is of a higher frequency than the previously reported one. In 3/28 children, a chromosome 3 abnormality was detected which was not visible using conventional cytogenetic analysis. We did not detect any 3p deletion. Increased copy number of 3q was found in four cases with trisomy of whole chromosome 3 and one case with 3q tetrasomy (isodisomy). We identified rare structural rearrangements in childhood acute myeloblastic leukemia, involving 3q21 and 3q26 loci around RPN1 and MDS1/EVI1 respectively. The poor outcome in pediatric patients with 3q rearrangements appears to be quite uniform.     

The significance of trisomy 8 in de novo acute myeloid leukaemia: the accompanying chromosome aberrations determine the prognosis

Trisomy 8 is the most frequent numerical chromosome aberration in acute myeloid leukaemia (AML). It occurs either as the sole anomaly or together with other clonal chromosome aberrations. We investigated whether accompanying chromosome anomalies influence the clinical outcome in patients with trisomy 8 and de novo AML. Since 1986, in 713 AML cases treated according to the protocols of the German AMLCG trials, chromosome analyses have been successfully performed. The overall incidence of trisomy 8 was 7.6%. Complete clinical follow-up data were available for 51 patients who were divided into three different categories: group 1: trisomy 8 as the sole cytogenetic anomaly ( n  = 20); group 2: trisomy 8 in addition to favourable chromosome aberrations (t(8;21)(q22;q22), t(15;17)(q22;q21), inv(16)(p13q22)) ( n  = 10); and group 3: trisomy 8 accompanied by other anomalies, in most cases of complex type ( n  = 21). Complete remission (CR) rates were 70%, 90% and 67% for groups 1, 2 and 3, respectively. Event-free survival (EFS) at 3 years differed significantly between patients with trisomy 8 only (37.5%), patients with trisomy 8 in combination with favourable aberrations (55.0%) and patients with trisomy 8 and other accompanying anomalies, mostly complex chromosome aberrations (9.0%) (group 1 v group 2: P  = 0.12; group 1 v group 3: P  = 0.005; group 2 v group 3: P  = 0.05). In this study patients with +8 as the sole cytogenetic anomaly had an intermediate prognosis, patients with +8 in addition to favourable chromosome aberrations maintained a good clinical outcome, and patients with +8 in combination with other abnormalities showed the worst prognosis.     

Cytogenetic studies in splenic lymphoma with villous lymphocytes

Summary. We report the cytogenetic findings on 31 cases of splenic lymphoma with villous lymphocytes (SLVL). TPA stimulated cells from peripheral blood (28 cases), spleen (two cases) and lymph node (one case) with SLVL have been analysed. A clonal chromosome abnormality was found in 27/31 patients (87%): this was identified as a simple abnormality in 12 cases and a complex one in 15. Four recurring abnormalities were seen: t(11:14) (q13:q32)in five patients, deletions or translocations involving 7q in seven patients. iso 17q in four patients and translocations involving 2p11 in four patients. The high frequency of clonal chromosome abnormalities in SLVL contrasts with the usually benign clinical course of this disease.
Abnormalities found frequently in patients with chronic lymphocytic leukaemia (CLL) such as trisosmy 12 and deletions or translocations involving 13q14 were each seen in only one patient. No case had the t(14:18) characteristic of follicular lymphoma.
Our findings demonstrate the high frequency of clonal and often complex chromosome abnormalities in SLVL. Although a unique chromosome rearrangement has not been identified, a pattern of four recurrent abnormalities has emerged. Our results suggest that SLVL is distinct on cytogenetic grounds from B-CLL and follicular lymphoma but shows similarity with mantle cell lymphoma, lymphoplasmacytic lymphoma and B-PLL.     

Structural aberrations of chromosomes 17 and 12 in chronic B-cell disorders

OBJECTIVES: Genomic aberrations can now be identified in approximately 80% of chronic lymphocytic leukemia, small lymphocytic lymphoma (CLL/SLL) patients. In the present study, four new structural changes involving chromosomes 17 and 12 in CLL/SLL patients are described. METHODS: Five patients were selected for inclusion in the present report among a total of 92 cases with diagnosis of CLL/SLL. Cytogenetic studies and fluorescence in situ hybridization (FISH) analysis to detect some of the most frequent cryptic aberrations occurring in CLL/SLL patients were performed. Clinical studies are also described. RESULTS: Four cases showed structural rearrangements of chromosome 17. A psu dic(17;2)(p11.2;p21), leading to p53 deletion, was observed in a patient who developed a mixed cellularity Hodgkin's disease coexisting with the CLL/SLL in the same lymph node. Epstein Barr virus was detected in the Reed-Sternberg cells. Two cases had a balanced translocation t(2;17)(p21;q23). Both patients showed trisomy 12 and clonal evolution and one of them also had 11q deletion. In addition, a der(17)t(12;17)(q13;q25) as a part of a complex karyotype, and a complex translocation t(5;12;19) (q15;p11;q13) were also found. Four patients had an adverse clinical outcome and died because of disease progression. CONCLUSIONS: Four unreported nonrandom chromosome aberrations in CLL/SLL patients, one of them who might represent a new recurrent abnormality, are described. These uncommon abnormalities, mostly associated with evolving disease, may have implications for the understanding of genetic events associated with disease progression in this pathology.     

Spontaneous acute lymphoblastic leukemia in Sprague-Dawley rats. II. Cytogenetic analysis of nine individual leukemias

Nine spontaneous acute lymphoblastic leukemias (SD1-SD9) in Sprague-Dawley rats were investigated cytogenetically by G-banding. The chromosome numbers of metaphase cells in all studied SD leukemias were near diploid and in all leukemias numerical or structural abnormalities were found. Affected were chromosomes No. 11, 2, 13 and 1. A common finding in most leukemias was trisomy 11 observed either as simple trisomy (SD1, SD4 and 2 clones of SD6), or the translocation form of trisomy (SD3), or the tandem translocation t(11;13) in SD7, or the Robertsonian fusion -rob(2;11) in SD5. In SD9 and one cell clone of SD8 no apparent trisomy was found, but the cells contained an 11q+ marker. Among the rearranged chromosomes, chromosome 2 was most frequently involved. Der No. 2 with terminal deletion was found in some of SD3 metaphases and a probable partial duplication of chromosome 2 was found in SD6. The finding of trisomy 2 in SD5 and SD6 occurred rarely. Further structural rearrangements concerned No. 13, the involvement of which was evident in the 13q+ marker typical of SD2, one cell clone of SD6, SD7 and SD8 leukemias. 1q+ aberration was the common finding in SD3 and SD5, while 1q-was observed in all SD6 metaphases. According to the cytogenetic examination of SD leukemias, we considered that the changes of chromosomes 11, 2, 13 and 1 were nonrandom. Based on the similarity of chromosomal rearrangements in individual leukemias, probable breakpoints on the affected chromosomes could be determined. 11cen, 11q12, 2q32-33, 2q16, 13q22, 1q43 and 1q54 were found to be the most frequently afflicted regions in SD leukemias.     

Splenic marginal zone B-cell lymphomas: two cytogenetic subtypes, one with gain of 3q and the other with loss of 7q

BACKGROUND AND OBJECTIVES: Splenic marginal zone B-cell lymphoma (SMZBCL) has clinical, immunophenotypic and histologic features distinct from other B-cell malignancies, but few chromosome studies have been previously reported. In the present study we performed conventional cytogenetics and in situ hybridization studies in 47 patients with SMZBCL. DESIGN AND METHODS: We studied 47 cases of splenic marginal zone B-cell lymphoma combining conventional cytogenetics and in situ hybridization (ISH) techniques using centromeric probes (chromosomes 3 and 12), locus specific probes (7q31 and 17p13) and cross-species color banding fluorescent ISH probes (RxFISH). The diagnosis of SMZBCL was ascertained in all cases after studying, morphologically and immunologically, peripheral blood and splenectomy specimens. RESULTS: A clonal chromosome abnormality detected by conventional cytogenetics and/or FISH was found in 33/47 patients (70%) being identified in 18 (18/33, 55%) as a complex abnormality. The most frequently recurrent abnormalities were: gain of 3q (10 cases), del(7q) (12 cases), and involvement of chromosomes 1, 8 and 14. No patient showed translocation t(11;14) (q13;q32) or t(14;18) (q21;q32). Trisomy 3 was detected in eight cases (8/47, 17%). Two novel cytogenetic abnormalities involving 14q32, t(6;14)(p12;q32) and t(10;14) (q24;q32) were reported. Deletion of 17p13 (P53) was observed by FISH in one case. Only one patient showed a gain of 3q or trisomy 3 and deletion 7q in the same karyotype. INTERPRETATION AND CONCLUSIONS: Our findings support the interpretation that two forms of SMZBCL could be considered, one with gain of 3q and the other with deletions at 7q.     

Chromosome aberrations and clinical features of adult T cell leukemia- lymphoma not associated with human T cell leukemia virus type I

Chromosome aberrations and clinical features of three patients with adult T cell leukemia-lymphoma (ATL) not associated with human T cell leukemia virus type I (HTLV-I) are described. From their clinical features, two patients were diagnosed as acute type and one patient was diagnosed as chronic type, which later converted to acute crisis. Clonal and many chromosomal abnormalities were observed before therapy in the two acute type cases and at relapse in the chronic type case. Karyotype aberrations, including trisomy 3, trisomy 7, trisomy 21, del(6)(q21), del(10)(p13), 14q11 translocation, and loss of X chromosome, all of which are frequently found in HTLV-I associated ATL, were also seen in these cases of HTLV-I-negative ATL.     

The significance of trisomy 8 in de novo acute myeloid leukaemia: the accompanying chromosome aberrations determine the prognosis

Trisomy 8 is the most frequent numerical chromosome aberration in acute myeloid leukaemia (AML). It occurs either as the sole anomaly or together with other clonal chromosome aberrations. We investigated whether accompanying chromosome anomalies influence the clinical outcome in patients with trisomy 8 and de novo AML. Since 1986, in 713 AML cases treated according to the protocols of the German AMLCG trials, chromosome analyses have been successfully performed. The overall incidence of trisomy 8 was 7.6%. Complete clinical follow-up data were available for 51 patients who were divided into three different categories: group 1: trisomy 8 as the sole cytogenetic anomaly (n = 20); group 2: trisomy 8 in addition to favourable chromosome aberrations (t(8;21)(q22;q22), t(15;17)(q22;q21), inv(16)(p13q22)) (n = 10); and group 3: trisomy 8 accompanied by other anomalies, in most cases of complex type (n = 21). Complete remission (CR) rates were 70%, 90% and 67% for groups 1, 2 and 3, respectively. Event-free survival (EFS) at 3 years differed significantly between patients with trisomy 8 only (37.5%), patients with trisomy 8 in combination with favourable aberrations (55.0%) and patients with trisomy 8 and other accompanying anomalies, mostly complex chromosome aberrations (9.0%) (group 1 v group 2: P = 0.12; group 1 v group 3: P = 0.005; group 2 v group 3: P = 0.05). In this study patients with +8 as the sole cytogenetic anomaly had an intermediate prognosis, patients with +8 in addition to favourable chromosome aberrations maintained a good clinical outcome, and patients with +8 in combination with other abnormalities showed the worst prognosis.     

Genetics and risk-stratified approach to therapy in chronic lymphocytic leukemia

The clinical staging systems developed by Rai and Binet have remained the mainstay for clinical decision-making in patients with chronic lymphocytic leukemia (CLL). However, there is substantial heterogeneity in the course of the disease. In recent years molecular and cellular markers have helped to predict the prognosis of patients with CLL. Ig V(H) status and genomic aberrations subdivide CLL into distinct clinical subgroups. Fluorescence in-situ hybridization (FISH) can identify genomic aberrations in approximately 80% of CLL cases. The most frequent aberrations are deletions in 13q, 11q, or 17p, and trisomy 12. Apart from providing insights into the pathogenesis, genomic aberrations identify subgroups of patients with distinct clinical pictures: lymphadenopathy (11q-) or resistance to therapy (17p-). Deletions at 11q and particularly 17p are associated with rapid disease progression or inferior survival. Patients with these genetic abnormalities may be candidates for clinical trials investigating alternative treatments and stem-cell transplantation.     

Clonal chromosomal abnormalities as direct evidence for clonality in nasal T/natural killer cell lymphomas

Nasal T/natural killer (NK) cell lymphoma is a distinct clinicopathologic entity which is more prevalent in Asia than in America and Europe. The clonal nature of the infiltrating lymphoid cells is difficult to demonstrate because of the lack of immunologic markers for clonality and the absence of clonal T-cell receptor gene rearrangement in most cases. In this study, clonal chromosomal abnormalities were detected in the tumour cells from four patients with nasal T/NK cell lymphoma. This finding provided direct evidence for clonality of the disease. Moreover, nonrandom cytogenetic abnormalities, including isochromosome for the short arm (p) of chromosome 6, isochromosome for the long arm (q) of chromosome 1, partial deletion of 6q, and aberrations at 11q, were disclosed. Isochromosome 6p was the sole structural abnormality in one patient, which may be a pathognomonic change in nasal lymphoma.     

Chromosome aberrations and cytogenetic intratumor heterogeneity in chondrosarcomas

Clonal chromosome aberrations identified after short-term culture are presented for 13 chondrosarcomas; in 5 cases both the primary tumors and local recurrences were studied. The stemline chromosome number was hypodiploid or hyperhaploid in 9 tumors. The most frequent numerical anomalies were, in falling order of frequency, loss of chromosomes Y, 10, 13, and 6, and gain of chromosomes 7 and 20. No recurrent structural rearrangement was found, but chromosome bands 5q13, 1q21, 7p11, and 20q11 were each involved in three different rearrangements. Karyotypic heterogeneity was assessed in two different ways: as the presence of more than one clone in one sample and as the presence of different clones in different samples from the same surgical specimen. Clonal karyotypic evolution was demonstrated in 6 of the 7 cases in which two or more samples could be investigated. All 6 showed intersample heterogeneity. Intrasample heterogeneity was found in only 5 of the 28 samples with aberrations. By comparing the incidences of the nonrandomly occurring aberrations in stemlines and sidelines in the heterogeneous tumors, it was possible to conclude that loss of chromosome 13 and rearrangement of band 5q13 were early events in the clonal evolution.Abbreviation EMC extraskeletal myxoid chondrosarcoma     

Cytogenic characterization of primary refractory anemia.

Refractory anemia (RA) is the only myelodysplastic syndrome (MDS) devoid of quantitative marrow diagnostic criteria. The diagnosis rests mainly on the subjective identification of qualitative abnormalities according to the French-American-British criteria (FAB) involving one or more bone marrow hematopoietic cell lineages. The occurrence of nonrandom chromosome abnormalities remains the hallmark of the disease and the only means of investigation which confirms the disease objectively. With the purpose in mind to further characterize RA among MDS, we have undertaken a prospective high resolution banding chromosome analyses of bone marrow cells in patients with primary refractory anemia (PRA) with the aim of defining a cytogenetic phenotype and of assessing the clinical relevance of clonal abnormalities at initial diagnosis. Of 39 patients consecutively referred for chromosome analyses with a diagnosis of RA according to the FAB criteria, 27 patients had PRA and fulfilled our criteria for adequate chromosome analyses. Median age was 68 years. Fourteen of 27 patients (52%) had clonal chromosomal abnormalities at diagnosis. None of the patients showed a complex karyotype; 9/14 (64%) had a mixture of normal and abnormal cells. Interstitial or terminal deletions, involving chromosomes 5, 6, 7, 9, 11, 12, and 20, were found in 11/14 (79%) of the patients. Comparison of survival between patients with and without abnormalities showed no difference. The presence of clonal abnormalities did not predict transformation to acute myeloblastic leukemia (AML) nor was it associated with poor survival. In this study, patients with PRA were found to have a predominant pseudodiploid karyotypic pattern characterized by interstitial and/or terminal deletions as opposed to derivatives, specific and non-specific balanced translocations, or other structural and numerical abnormalities. We were unable to reveal any prognostic significance to the presence of these clonal abnormalities at initial diagnosis.