Comparison of cytogenetic and molecular genetic detection of t(8;21) and inv(16) in a prospective series of adults with de novo acute myeloid leukemia: a Cancer and Leukemia Group B Study.

PURPOSE: To prospectively compare cytogenetics and reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of t(8;21)(q22;q22) and inv(16)(p13q22)/t(16;16)(p13;q22), aberrations characteristic of core-binding factor (CBF) acute myeloid leukemia (AML), in 284 adults newly diagnosed with primary AML. PATIENTS AND METHODS: Cytogenetic analyses were performed at local laboratories, with results reviewed centrally. RT-PCR for AML1/ETO and CBFbeta/MYH11 was performed centrally. RESULTS: CBF AML was ultimately identified in 48 patients: 21 had t(8;21) or its variant and AML1/ETO, and 27 had inv(16)/t(16;16), CBFbeta/MYH11, or both. Initial cytogenetic and RT-PCR analyses correctly classified 95.7% and 96.1% of patients, respectively (P =.83). Initial cytogenetic results were considered to be false-negative in three AML1/ETO-positive patients with unique variants of t(8;21), and in three CBFbeta/MYH11-positive patients with, respectively, an isolated +22; del(16)(q22),+22; and a normal karyotype. The latter three patients were later confirmed to have inv(16)/t(16;16) cytogenetically. Only one of 124 patients reported initially as cytogenetically normal was ultimately RT-PCR-positive. There was no false-positive cytogenetic result. Initial RT-PCR was falsely negative in two patients with inv(16) and falsely positive for AML1/ETO in two and for CBFbeta/MYH11 in another two patients. Two patients with del(16)(q22) were found to be CBFbeta/MYH11-negative. M4Eo marrow morphology was a good predictor of the presence of inv(16)/t(16;16). CONCLUSION: Patients with t(8;21) or inv(16) can be successfully identified in prospective multi-institutional clinical trials. Both cytogenetics and RT-PCR detect most such patients, although each method has limitations. RT-PCR is required when the cytogenetic study fails; it is also required to determine whether patients with suspected variants of t(8;21), del(16)(q22), or +22 represent CBF AML. RT-PCR should not replace cytogenetics and should not be used as the only diagnostic test for detection of CBF AML because of the possibility of obtaining false-positive or false-negative results.

Cyclin D2 promoter disrupted by t(12;22)(p13;q11.2) during transformation of chronic lymphocytic leukaemia to non-Hodgkin's lymphoma.

In a unique case of chronic lymphocytic leukaemia (CLL) we performed a longitudinal cytogenetic and molecular genetic study of tumour cells from diagnosis through progression and transformation to non-Hodgkin's lymphoma (NHL) and lymphomatous meningitis. CLL cells at diagnosis had trisomy 12 and a t(14;19)(q32;q13.3). At relapse, the leukaemic cells had a subclone carrying a t(12;22)(p13;q11.2) in addition to the initial changes. We cloned reciprocal translocation junctions at the 22q11.2- chromosome and the 12p13+ chromosome and the corresponding germline DNA fragments. Restriction map analysis and nucleotide sequence analysis of the cloned DNA fragment from the 22q11.2- chromosome mapped the translocation break within the immunoglobulin (Ig)-lambda-C complex at the nt3889; nts 3890, 3891 were lost from the translocation site. A probe from the 3'-end of the clone derived from the 22q11.2- chromosome showed single copy hybridization which was different from the Ig-lambda probe. Nucleotide sequence analysis of the exact junction region and the corresponding germline DNA showed that the translocation at 12p13 occurred in the negative regulatory region of the cyclin D2 gene at the nt -1602, and a pentamer consisting of nts -1603 to -1599 was lost at the break site. We sequenced another 227 bp upstream of the known 5'-end of the promoter and did not find any open reading frame. From these results we hypothesize that, in this patient, the t(12;22) disrupted the negative regulator in the promoter of cyclin D2 which in turn might have deregulated cyclin D2.

Adult patients with de novo acute myeloid leukemia and t(9; 11)(p22; q23) have a superior outcome to patients with other translocations involving band 11q23: a cancer and leukemia group B study.

Following reports of childhood acute myeloid leukemia (AML) showing that patients with t(9; 11)(p22; q23) have a better prognosis than those with translocations between 11q23 and other chromosomes, we compared response to therapy and survival of 24 adult de novo AML patients with t(9; 11) with those of 23 patients with other 11q23 translocations [t(11q23)]. Apart from a higher proportion of French-American-British (FAB) M5 subtype in the t(9; 11) group (83% v 43%, P = .006), the patients with t(9; 11) did not differ significantly from patients with t(11q23) in terms of their presenting clinical or hematologic features. Patients with t(9; 11) more frequently had an extra chromosome(s) 8 or 8q as secondary abnormalities (46% v 9%, P = .008). All patients received standard cytarabine and daunorubicin induction therapy, and most of them also received cytarabine-based intensification treatment. Two patients, both with t(9; 11), underwent bone marrow transplantation (BMT) in first complete remission (CR). Nineteen patients (79%) with t(9; 11) and 13 (57%) with t(11q23) achieved a CR (P = .13). The clinical outcome of patients with t(9; 11) was significantly better: the median CR duration was 10.7 versus 8.9 months (P = .02), median event-free survival was 6.2 versus 2.2 months (P = .009), and median survival was 13.2 versus 7.7 months (P = .009). All patients with t(11q23) have died, whereas seven (29%) patients with t(9; 11) remain alive in first CR. Seven of eight patients with t(9; 11) who received postremission regimens with cytarabine at a dose of 100 (four patients) or 400 mg/m2 (2 patients) or who did not receive postremission therapy (2 patients) have relapsed. In contrast, 7 (64%) of 11 patients who received intensive postremission chemotherapy with high-dose cytarabine (at a dose 3 g/m2) (5 patients), or underwent BMT (2 patients) remain in continuous CR. We conclude that the outcome of adults with de novo AML and t(9; 11) is more favorable than that of adults with other 11q23 translocations; this is especially true for t(9; 11) patients who receive intensive postremission therapy.

Correlation between mutation in P53, p53 expression, cytogenetics, histologic type, and survival in patients with B-cell non-Hodgkin's lymphoma.

In the biology of a cell, the central role of p53 in controlling functions such as G1/S transition (check point) and DNA damage repair, and as a trigger of apoptosis, is well established. Somatic mutations or other changes in P53 have been reported in numerous tumor types, and in some of these, they are associated with poor prognosis. In this study, we examined 237 cytogenetically characterized B-cell non-Hodgkin's lymphomas (B-NHLs) for somatic changes in P53 by Southern blot analysis, by single-strand conformation polymorphism analysis (SSCP) of exon 5 through 9, and by direct sequencing of SSCP variants to determine the frequency and types of mutations and their clinical significance. In a portion of these (173 tumors), we also studied p53 expression by immunostaining. On Southern blots, no gross change was identified in P53 and no mutation was identified in exon 9. In exons 5 through 8, 27 different mutations were identified in 25 patients (23 single-base substitutions, 3 deletions, 1 duplication). Mutations in P53 were identified in 25 of 237 tumors (10.5%), which included 1 of 45 small lymphocytic lymphomas (SLLs), 2 of 38 follicular small cleaved-cell lymphomas (FSCCs), 2 of 35 follicular mixed small cleaved-cell and large-cell lymphomas (FMxs), 1 of 4 follicular large-cell lymphomas (FLCs), 1 of 14 diffuse small cleaved-cell lymphomas (DSCCs), 2 of 17 diffuse mixed small- and large-cell lymphomas (DMxs), and 16 of 84 diffuse large-cell lymphomas (DLCCs); the difference between the histologic groups was significant (P < .01). Among mantle-cell lymphoma (MC) patients, 3 of 10 had mutations. In 16 patients, the mutation was identified in specimens obtained at diagnosis. Mutation of transition type and transversion type occurred at a relative frequency of 2:1. Thirty percent occurred at CpG dinucleotide sequences and the codon for arginine was most frequently affected. Nineteen of 99 tumors with complex cytogenetic abnormalities, but none of 69 tumors with simple cytogenetic abnormalities, had mutations (P < .001). Similarly, 11 of 25 tumors with an abnormality of 17p and 8 of 143 tumors with apparently normal 17p had mutations (P < .0001). Positive correlations were found between a mutation and p53 expression (P < .001), between missense type mutations and p53 expression (P < .005), and between 17p abnormalities and p53 expression (P < .05). Twenty-two of 49 patients without mutation and 14 of 17 patients with mutations died (P < .05), but there was no significant difference in median survival. Similarly, 21 of 26 p53 positive patients died, whereas only 1 of 24 p53-negative patients died on-study (P < .001). Among p53-negative patients, mutation (P < .01) was positively associated with a fatal outcome. These findings indicate that in B-NHL, somatic changes in P53 were present in diagnostic specimens of all histologic types, but at a higher frequency in DLC and MC tumors. P53 mutation and/or expression has a negative influence on survival, and therefore can serve as prognostic indicators. Immunostaining for p53 is an effective way to screen for P53 changes in these tumors.

Clinical and morphological features of cases of trisomy 13 in acute non-lymphocytic leukemia.

Trisomy 13 has been infrequently reported as a primary non-random karyotypic change in myeloid leukemias. To elucidate its clinical significance we examined the clinical and hematological data in nine ANLL patients in whom we found this change, in a series of 175 cytogenetically abnormal ANLL patients. Morphologically, six of the patients were FAB-M1, two were FAB-M4 and one was FAB-M5. Bone marrow aspirates contained more than 90% blasts in eight of the patients. By immunophenotype, TdT was present in four of the patients, CD34 was present in four of five patients tested and CD5 was present in one of five patients tested. Blast cells in all patients expressed two or more myeloid surface antigens. These data suggest the proliferation of an immature myeloid cell in these patients. Complete remission was achieved in seven patients; however, remissions were short-lived. Eight patients expired between 1 and 13 months from diagnosis (median survival 5 months). Combining our findings with data in the published literature on trisomy 13 in ANLL, a larger data set consisting of 29 patients was established to determine better the clinical significance of this cytogenetic entity in ANLL. We found that this cytogenetic change has been reported in all subsets of FAB classification excepting M6 and M7. Median age at presentation was 60 years and no association with gender was noted. Median WBC was 29.5 x 10(9)/l, the majority of patients were thrombocytopenic (median platelet count 86 x 10(9)/l) and median survival was 5.2 months. This study associates trisomy 13 with malignant transformation of myeloid progenitor cells. These patients respond well to induction therapy, but relapse occurs quickly and the survival duration is poor.

Deletion of cyclin-dependent kinase 4 inhibitor genes P15 and P16 in non-Hodgkin's lymphoma.

B-cell non-Hodgkin's lymphoma (NHL) is a heterogeneous lymphoid malignancy consisting of several histologic types. Alterations in proto-oncogenes caused by reciprocal chromosome translocations have been implicated in the etiology of specific histologic groups. In this study, we examined the contribution of the cell cycle inhibitor genes P15, P16, and P18 to pathogenesis in a large panel of 209 cytogenetically characterized B-cell NHL tumors representing varied histologic groups. We identified the homozygous deletion of P15 and P16 genes in 13 tumors from 12 patients, all belonging to diffuse large-cell histology; 10 had this diagnosis made on presentation, 1 had transformed from small lymphocytic lymphoma, and 1 had transformed from Hodgkin's disease. Tumor-specific point mutations were not identified in the coding regions of these genes. Cytogenetically, chromosome 9p was normal in all but one tumor. On the other hand, eight tumors hemizygous for 9p by cytogenetic analysis showed wild-type configuration of these genes. Our study, therefore, indicates that deletion of P15 and P16 occurs in about 15% of diffuse large-cell NHL and is not usually detected by cytogenetic analysis. P18 was wild-type in all tumors including the 13 tumors hemizygous for 1p.

Morphological, ultrastructural, and genetic characterization of an unusual T-cell lymphoma in a patient with sinus histiocytosis with massive lymphadenopathy.

Sinus histiocytosis with massive lymphadenopathy (SHML) is a rare benign disease of unknown etiology. It is rarely associated with malignant lymphoma. This report documents the first case of a T-cell lymphoma, which developed in a patient with a 10-year history of SHML. The disease was complicated by hypereosinophilia and massive retroperitoneal lymphadenopathy. Histological examination of a cervical lymph node biopsy during the terminal phase identified a lymphoma composed of cells with morphological plasmacytoid features. Ultrastructurally, the tumor cells showed poorly developed cytoplasm, nuclei with peripheral chromatin clumping, and inconspicuous nucleoli. Cytogenetic studies showed two related clones. On immunohistochemical staining tumor cells were positive with monoclonal antibodies (mAb) CD3 and CD45RO. Southern blotting analysis identified clonal rearrangements in the T-cell receptor (TCR) alpha, beta and gamma genes. Thus, T-cell lineage of the tumor cells was established. In situ hybridization of interleukin-2 (IL-2) and interleukin-5 (IL-5) cDNA probes on tissue sections identified the synthesis of IL-5 by the eosinophils, suggesting an autocrine pathway of eosinophilopoiesis leading to hypereosinophilia in this patient.

Molecular characterization of a variant Ph1 translocation t(9;22;11) (q34;q11;q13) in chronic myelogenous leukemia (CML) reveals the translocation of the 3'-part of BCR gene to the chromosome band 11q13.

We performed cloning and sequence analysis of translocation junctions at 11q- and 22q- (Ph1) chromosomes and the corresponding germline DNAs of a variant Ph1-positive CML with t(9;22;11)(q34;q11;q13). Southern blot analysis using probes for different regions of bcr mapped the translocation break near the 5'-side of bcr exon 4. Cloning, Southern blot analysis and restriction map analysis of both bcr fragments showed that the part of bcr 3'- to the translocation break moved to 11q13. Sequence analysis of the translocation junction on the Ph1 chromosome showed that the translocation break occurred 63 bp upstream of exon 4. Compared to the germline sequence, bcr sequence from the translocated partners showed deletion of seven basepairs at the site of translocation. A probe derived from the 5'-region of the clone isolated from the 11q- chromosome identified clonal rearrangements in the leukemic DNA. Restriction map and sequence analysis showed that this clone consisted of the 3'-half of the glutathione S-transferase Pi (GST-Pi) gene and the 3'-part of bcr. We identified two point mutations in the GST-Pi allele involved in translocation. Northern blot analysis showed that the GST-Pi gene was expressed in the leukemic cells at blast crisis but not at chronic phase; however, no fusion mRNA between GST-Pi and bcr was identified. We did not find any sequence homology between 11q13 DNA and 22q11 DNA around the translocation breakpoints; however, sequences homologous to ALU repeats were identified close to the sites of translocation breaks at 22q11 and 11q13. This study supports our hypothesis that variant Ph1 translocations may occur as primary cytogenetic changes similar to the classical Ph1 translocations.

Serial phenotypic, cytogenetic and molecular genetic studies in Richter's syndrome: demonstration of lymphoma development from the chronic lymphocytic leukaemia cells.

In this report we describe a unique longitudinal study on the clinical, phenotypic, cytogenetic and molecular genetic features of malignant cells from diagnosis of chronic lymphocytic leukaemia (CLL) to the development of lymphoma and lymphomatous meningitis. CLL cells at diagnosis were CD5+, CD19+, surface IgG+, kappa+, were karyotypically abnormal and showed clonal rearrangements in the immunoglobulin heavy (IgH) and kappa light chain genes. Phenotypically leukaemic cells and lymphoma cells at RS resembled CLL at diagnosis, but showed cytogenetic evolution. Geometrically leukaemic cells and lymphoma cells retained the initial clonal rearrangements in IGH and kappa genes, but showed additional supervening clonal rearrangements in both of these genes as the disease progressed to RS. Furthermore, the c-lambda DNA showed clonal rearrangements in the leukaemic cells and lymphoma cells at RS. This complete phenotypic and genotypic analysis of tumour cells during the course of the disease demonstrates the origin of lymphoma from CLL cells through progressive cytogenetic and molecular genetic changes in CLL cells.

Phenotypic and genotypic characterization of Hodgkin's disease.

Although a few studies have reported clonal cytogenetic changes in Hodgkin's disease (HD), their correlation with histologic groups is poorly defined. This is because of insufficient numbers of clonally abnormal cases ascertained in each of these studies, an inherent problem associated with the cytogenetic studies of HD. In this report we present results of pathologic, phenotypic, and genetic studies on 29 HD tumors consecutively ascertained by us and the results of a comprehensive analysis of the cytogenetic data available in the literature. In our series 75% of the tumors were positive for Epstein-Barr virus (EBV) by polymerase chain reaction (PCR) assay. A higher frequency of EBV-positive tumors showed clonal karyotypic abnormalities than the EBV-negative tumors. Unlike the case in the previous reports, none of the 24 tumors studied by PCR showed the presence of t(14;18) (q32;q21)-carrying cells. From the comprehensive analysis of the literature, we identified recurring nonrandom numerical changes, deletions, and chromosome breaks in HD. Some of these are associated either with nodular sclerosis or with mixed cellular histologies. A comparison of the pattern of these nonrandom cytogenetic changes in HD and those reported for non-Hodgkin's lymphomas (NHL) identified common deletions and breaks between them. These common genetic lesions probably play a role in disease evolution.

Novel restriction fragment length polymorphisms in the cellular oncogene SEA.

The human homologue of the SEA oncogene has been mapped recently to chromosome band 11q13. While studying the possible involvement of this gene in the variant translocation t(9;22;11) (q34;q11;q13) in a case of chronic myelogenous leukemia, we identified novel polymorphisms for XbaI and SacI restriction enzyme sites in the SEA gene. Frequency of the polymorphic alleles was studied in 100 samples from healthy controls, 94 samples from patients with non-Hodgkin's lymphoma, 25 samples from patients with benign lymphadenopathy, and 38 samples from patients with chronic myelogenous leukemia. XbaI digestion showed a three-allele polymorphism with two frequent alleles A (8.0 kb) and B (9.2 kb) and a rare allele (5.8 kb). After SacI digestion the probe identified two primary genotypes. Genotype I showed two hybridizable DNA fragments, one each of 6.6 and 3.5 kb. In genotype II the 3.5 kb fragment was absent, instead two smaller fragments, one each of 1.9 kb and 1.6 kb were present. The 6.6 kb fragment (allele AA) had three polymorphic sites generating 6.2 kb fragment (allele BB), 7.4 kb fragment (allele CC), and 7.8 kb fragment (allele DD). Frequencies of the two genotypes and the four alleles followed Mendelian proportions in all the samples studied. Furthermore, this study shows the importance of restriction map analysis of DNA in the vicinity of the probe of an oncogene to distinguish natural polymorphisms from the disease-related rearrangements in the gene.

Molecular structure of double reciprocal translocations: significance in B-cell lymphomagenesis.

The molecular structure of reciprocal translocations associated with low grade and high grade non-Hodgkin's lymphomas occurring together was analysed in two tumors. Sequential biopsies documented histological transformation of a large cell lymphoma to an immunoblastic lymphoma bearing t(14;18)(q32;q21) and t(8;22)(q24;q11). A second tumor, a small non-cleaved cell lymphoma, demonstrated a t(8;14)(q24;q11) as well as t(18;22)(q21;q11). DNA analysis from these tumors showed rearrangements at the Ig heavy chain, kappa and lambda light chains, BCL2 and c-MYC loci. Utilizing multiple enzyme digests and different probes spanning the BCL2, c-MYC and Ig genes, mapping of DNA break-points was performed. In both these tumors primary translocation events dysregulating the BCL2 or c-MYC were identified to have occurred in a pre-B-cell. Based on these results and those published previously, a sequence of B-cell development during which somatic recombination errors lead to the genesis of specific translocations is proposed. From these studies it is inferred that secondary dysregulation of a c-MYC in a lymphoma tumor carrying dysregulated BCL2 gene leads to rapid progression to high grade disease.

Genetic origin of a trophoblastic choriocarcinoma.

Gestational choriocarcinoma can follow a term birth, a nonmolar abortion, or a complete hydatidiform mole. Among hydatidiform moles, heterozygous ones resulting from fertilization of an egg devoid of a nucleus by a diploid sperm (XY) or by dispermy (XX or XY) have been suggested to carry an increased predisposition to transformation to choriocarcinoma. Data on genetic analysis of choriocarcinoma are meager, being limited to cytogenetic analysis of a handful of established cell lines. Although the majority of these were heterozygous, antecedent pregnancies or molar tissues have not been investigated in any of them to clearly establish their genetic origin. We present here the results of a study of chromosomal heteromorphisms and DNA restriction fragment length polymorphisms in a choriocarcinoma, the host, her spouse, and her son from the antecedent pregnancy. Our data show that the choriocarcinoma in this case most probably arose from the product of the same fertilization that led to the antecedent pregnancy.

Cytogenetic and molecular genetic analysis of abnormal cells in Hodgkin's disease.

Eleven tumors from ten patients with Hodgkin's diseases (HD) were characterized by histologic, cytogenetic, immunophenotypic, and genotypic studies. Cell surface markers for lymphocyte antigens did not show clonal excess. Five tumors showed the presence of karyotypically abnormal cells, but no common abnormalities were found. The remaining six tumors showed normal karyotypes. Ten tumors were analyzed for gene rearrangements with probes for IgJH, IgCk. IgC lambda, and TCR-beta genes. The IgJH probe detected a minor clonal population (about 5%) in one tumor with abnormal karyotype; three tumors with abnormal karyotypes showed germline genotype. In contrast, four of the six tumors with normal karyotypes showed rearrangements in IgJH (one tumor) and in C-lambda (three tumors) genes. The pattern of gene rearrangement observed in these tumors did not obey the hierarchy described in B-cell differentiation. These results suggest that B-cell lineage cannot be attributed unequivocally to the clonal populations in HD.

Molecular analysis of breaks in BCL-1 proto-oncogene in B-cell lymphomas with abnormalities of 11q13.

The t(11;14)(q13;q32) is a recurring translocation that occurs infrequently but non-randomly in B-cell chronic lymphocytic leukemia, B-cell non-Hodgkin's lymphoma, and multiple myeloma. The putative oncogene BCL-1 located at the chromosomal band 11q13 has been cloned previously from a B-cell CLL with t(11;14). We studied the molecular structure of the BCL-1 gene in eight B-cell NHL tumors that exhibited a break at 11q13. The cytogenetic changes in these tumors were t(11;14) in three, t(1;11;14)(q32;q13;q32) in two and dup(11)(pter----q23::11q13----ter) in three. The BCL-1 gene was found to have rearranged in two tumors. By Southern blot analysis of single and double digested DNA from placenta and from the tumors, we mapped the breakpoint in BCL-1 to a 0.5 kb Pst-I-HindIII restriction fragment which was approximately 2kb away from the sites of previously mapped breakpoints. Sequential hybridization of Southern blots of these tumors with different immunoglobulin probes (for J region, Cu, Su) and BCL-1 probe identified co-migrating fragments with Su probe after BamHI restriction digestion. These results demonstrate that translocation breaks in the BCL-1 gene are not clustered in a short stretch of DNA at 11q13, and that the translocation related breaks in the immunoglobulin heavy chain can occur outside the joining region. The implications of these observations to the genesis of chromosomal translocations during B cell development are discussed.

Molecular analysis of structural chromosome changes affecting chromosome band 11q23.

Involvement of the ets-1 proto-oncogene located at chromosome band 11q23 was studied in six tumors and in a congenital chromosome abnormality affecting the 11q23 region, in order to determine whether the breakpoint of these rearrangements was identical at the molecular level. In multiple restriction digestions a 5.4 kb EcoRI genomic probe of the c-ets-1 gene did not detect rearrangements in any of these samples. Thus, in these tumors the break in DNA was not within the domain of c-ets-1 recognized by this probe. However, after digestion with XbaI enzyme the probe detected a 2.4 kb polymorphic allele in placental DNA. One tumor DNA sample showed homozygosity for this polymorphic allele. In order to determine the frequency of this polymorphic allele, DNA from 50 additional tumors and from the blood of nine healthy donors was analyzed. DNA from one tumor showed homozygosity for the polymorphic allele. In the 67 DNA samples studied, 17.9 per cent were heterozygous for the polymorphic site and 3 per cent were homozygous for the polymorphic site. Thus, the overall frequency of the polymorphic allele in these samples was 0.111.

Non random cytogenetic changes characterize Merkel cell carcinoma.

Merkel cell carcinoma is a rapidly proliferating neoplasm of neuroectodermal origin presenting in skin. Karyotypes obtained in direct preparations of three Merkel cell carcinomas were analyzed and compared with six other tumors which were reported in the literature. Of the nine tumors studied so far, eight (89 per cent) showed structural abnormalities of chromosome 1. These abnormalities were in the form of trisomy for chromosome 1q22----ter. Furthermore, it was also observed that the breaks of these rearrangements on chromosome 1 occurred at the bands to which c-oncogenes N-ras (p31), L-myc (p32), c-src (p36), c-ski (q22-22), and the beta-subunit of the nerve growth factor (NGF) (p22) were localized. In addition to structural changes, five out of the nine tumors (55.5 per cent) were trisomic for chromosome 1. Merkel cell tumors are often confused with small cell carcinoma of lung or peripheral neuroepithelioma. The cytogenetic abnormalities such as rearrangement of chromosome 3p and t(11;22)(q23;q12) which characterize lung carcinoma and peripheral neuroepithelioma, respectively, were not seen in any of the nine Merkel cell tumors studied. Thus it appears that rearrangement of chromosome 1 was non-randomly associated with Merkel cell carcinoma. It is of interest to note that genes involved in neuronal development and or differentiation have been mapped to the bands at which breaks occurred in these tumors. The significance of these changes is briefly discussed.

18q21 rearrangement in diffuse large cell lymphoma: incidence and clinical significance.

Cytogenetic, molecular genetic and clinical information was collected for 102 cases of diffuse large cell lymphoma (DLCL) ascertained in a diagnostic laboratory over a 3-year period. Nineteen cases showed evidence of either a t(14;18) or a rearrangement of one of three genomic probes for breakpoints at 18q21. Clinical and histologic evidence of transformation from follicular lymphoma or chronic lymphocytic leukaemia was available in six cases. Except for age, prognostic clinical variables (LDH, stage, extranodal involvement) were similar between the 18q21 rearranged patients and DLCL patients without 18q21 rearrangement. At a median follow-up in excess of 2 years for both groups, there was no difference in overall survival between the 18q21 rearranged group compared to DLCL patients lacking this genetic abnormality. The median disease-free survival for the 18q21 rearranged group, however, was significantly shorter and survival in partial remission longer. The propensity for extended survival of the 18q21 rearranged DLCL patients with residual or recurrent disease resembled the clinical behaviour of nodular lymphoma patients with t(14;18). These results suggest that cytogenic or molecular genetic identification of a chromosome 18q21 translocation may be of prognostic significance in the analysis of treatment protocols for patients with DLCL.

Meiotic chromosome segregation in human t(11;22)(q23;q11) carriers: a theoretical consideration.

The t(11;22)(q23;q11) translocation is the most frequently encountered familial reciprocal translocation in humans. In the majority of reported cases ascertainment has been through the birth of a child with the chromosomal constitution 47,XX,+der(22) or 47,XY,+der(22), i.e., tertiary trisomy. Previous segregation analysis of familial cases showed a number of interesting features. Thus, euploid unbalanced genotypes resulting from adjacent segregation are absent in the progeny, and only tertiary trisomic offspring are recovered. To explain this unusual progeny output we present here a model for the meiotic behavior of this translocation in the carriers based on an analysis of cytogenetic data of progeny of carriers. This model predicts the formation of a chain trivalent with chromosome order 11-der(11)-22 during prophase I and its predominant alternate orientation at metaphase I.

Nonrandom chromosomal aberrations are associated with sites of tissue involvement in non-Hodgkin's lymphoma.

In an effort to assess the utility of pretreatment cytogenetics as indicators of sites of involvement by lymphoma, clinical and cytogenetic correlations were performed on 133 consecutive specimens derived from 130 patients with non-Hodgkin's lymphoma. Nonrandom chromosomal aberrations detected at the time of diagnosis were associated with sites of clinical involvement presenting initially or during the progression of the lymphoma. Statistically significant associations included translocation breaks involving the chromosomal region 1p32-36 and bone marrow involvement, chromosome 14 abnormalities including breaks at 14q22-24 and splenic involvement, chromosome 9 abnormalities and pulmonary involvement, and monosomy 11 and bone involvement. A significant correlation was also observed between breaks involving the region 6q22-24, detected during the course of disease, and bone marrow involvement by lymphoma. The relationship of the sites of nonrandom chromosomal breakage reported here to known cellular oncogenes and implications to concepts of tumor evolution and spread are discussed.