Biomedical subjects

M Höglund

Publications and source records attributed to M Höglund.

At least 19 recordsLinked to original sources

PubMed2006

Genomic profiling of bone and soft tissue tumors with supernumerary ring chromosomes using tiling resolution bacterial artificial chromosome microarrays.

Ring chromosomes and/or giant marker chromosomes have been observed in a variety of human tumor types, but they are particularly common in a subgroup of mesenchymal tumors of low-grade or borderline malignancy. These rings and markers have been shown to contain amplified material predominantly from 12q13-15, but also sequences from other chromosomes. Such amplified sequences were mapped in detail by genome-wide array comparative genomic hybridization in ring-containing tumor samples from soft tissue (n = 15) and bone (n = 6), using tiling resolution microarrays, encompassing 32 433 bacterial artificial chromosome clones. The DNA copy number profiles revealed multiple amplification targets, in many cases highly discontinuous, leading to delineation of large numbers of very small amplicons. A total number of 356 (median size: 0.64 Mb) amplicons were seen in the soft tissue tumors and 90 (median size: 1.19 Mb) in the bone tumors. Notably, more than 40% of all amplicons in both soft tissue and bone tumors were mapped to chromosome 12, and at least one of the previously reported recurrent amplifications in 12q13.3-14.1 and 12q15.1, including SAS and CDK4, and MDM2, respectively, were present in 85% of the soft tissue tumors and in all of the bone tumors. Although chromosome 12 was the only chromosome displaying recurrent amplification in the bone tumors, the soft tissue tumors frequently showed recurrent amplicons mapping to other chromosomes, that is, 1p32, 1q23-24, 3p11-12, 6q24-25 and 20q11-12. Of particular interest, amplicons containing genes involved in the c-jun NH2-terminal kinase/mitogen-activated protein kinase pathway, that is, JUN in 1p32 and MAP3K7IP2 (TAB2) in 6q24-25, were found to be independently amplified in eight of 11 cases with 12q amplification, providing strong support for the notion that aberrant expression of this pathway is an important step in the dedifferentiation of liposarcomas.

Adult↗

PubMed2006

Molecular characterization of early-stage bladder carcinomas by expression profiles, FGFR3 mutation status, and loss of 9q.

We used gene expression profiling, mutation analyses of FGFR3 and TP53, and LOH analyses of chromosome 9 and the TP53 region on chromosome arm 17p, to molecularly characterize 75 Ta and T1 bladder carcinomas. We identified four major cellular processes related to cell cycle, protein synthesis, immune response, and extra cellular components that contribute to the expressional heterogeneity of early-stage urothelial cell carcinoma (UCC). Activating FGFR3 mutations were found at the highest frequency in G1 tumors (80%), and showed a strong correlation with FGFR3 expression. In contrast, G3 tumors displayed mutations in less than 10% of the cases and a low level of FGFR3 expression. Even though LOH on chromosome 9 was not associated with any specific expression pattern, our data indicate that loss of chromosome 9 is associated with tumor development rather than initiation. The combined analyses suggest the existence of two types of UCC tumors, one which is characterized by FGFR3 mutation or expression, high expression of protein synthesis genes, and low expression of cell cycle genes. Furthermore, the presented data underscore FGFR3 receptor involvement in urothelial cell transformation as the presence of FGFR3 mutations has a major impact on the global gene expression profile of bladder carcinomas.

Chromosomes, Human, Pair 17↗

PubMed2006

A gene fusion network in human neoplasia.

Cancer is, at the cellular level, a genetic disease and acquired gene fusions play a causal role in the initiation of the neoplastic process either by activating proto-oncogenes or creating hybrid genes. We constructed a network by combining the 5' and 3' parts of all presently known gene fusions in human neoplasia and here we show that the observed network is fragmented and that the organization of the genes demonstrates a scale-free network topology with a power law degree distribution meeting the requirements of P(k) approximately k(-gamma), that is, conforming to the distributions found in naturally occurring networks such as the Internet and social or ecological networks. The results hence indicate that the complex system of pairwise interacting genes leading to neoplasia is governed by a universal principle.

Algorithms↗

PubMed2006

Truncation and fusion of HMGA2 in lipomas with rearrangements of 5q32-->q33 and 12q14-->q15.

Chromosome segment 12q13-->q15 recombines with many different chromosome bands in lipomas and at least ten recurrent translocations have been identified. The HMGA2 gene is often rearranged, but little is known about the molecular consequences at other breakpoints. Fusion genes between HMGA2 (12q14-->q15) and LPP (3q27-->q28), LHFP (13q12) and CMKOR1 (2q37) have been reported. In the present study, eight lipomas with rearrangements involving chromosome bands 12q14-->q15 and 5q32-->q33 were analyzed. In chromosome 5, five of the cases had a breakpoint in the 5' part of EBF in 5q33, while three cases had breakpoints located about 200 kb 3' of EBF. In chromosome 12, the breakpoints clustered to the region of HMGA2. Four cases had breaks within the gene and four had breaks 5' to HMGA2 where the gene BC058822 is located. Two versions of an HMGA2/EBF fusion transcript were detected in one case; one transcript was in frame and the other out of frame. Identical EBF/BC058822 fusion transcripts, seen in two cases, one of which also had the HMGA2/EBF transcript, were out of frame and resulted in truncation of EBF. Since EBF and HMGA2 have different orientations, the findings must be explained by complex aberrations including multiple breaks. The combined data indicate that the pathogenetically significant event is fusion, truncation or transcriptional activation of HMGA2, but it can not be excluded that EBF, which has been implicated in adipogenesis, contributes to the tumor development.

Adult↗

PubMed2005

Gene expression profiling of leukemic cell lines reveals conserved molecular signatures among subtypes with specific genetic aberrations.

Hematologic malignancies are characterized by fusion genes of biological/clinical importance. Immortalized cell lines with such aberrations are today widely used to model different aspects of leukemogenesis. Using cDNA microarrays, we determined the gene expression profiles of 40 cell lines as well as of primary leukemias harboring 11q23/MLL rearrangements, t(1;19)[TCF3/PBX1], t(12;21)[ETV6/RUNX1], t(8;21)[RUNX1/CBFA2T1], t(8;14)[IGH@/MYC], t(8;14)[TRA@/MYC], t(9;22)[BCR/ABL1], t(10;11)[PICALM/MLLT10], t(15;17)[PML/RARA], or inv(16)[CBFB/MYH11]. Unsupervised classification revealed that hematopoietic cell lines of diverse origin, but with the same primary genetic changes, segregated together, suggesting that pathogenetically important regulatory networks remain conserved despite numerous passages. Moreover, primary leukemias cosegregated with cell lines carrying identical genetic rearrangements, further supporting that critical regulatory pathways remain intact in hematopoietic cell lines. Transcriptional signatures correlating with clinical subtypes/primary genetic changes were identified and annotated based on their biological/molecular properties and chromosomal localization. Furthermore, the expression profile of tyrosine kinase-encoding genes was investigated, identifying several differentially expressed members, segregating with primary genetic changes, which may be targeted with tyrosine kinase inhibitors. The identified conserved signatures are likely to reflect regulatory networks of importance for the transforming abilities of the primary genetic changes and offer important pathogenetic insights as well as a number of targets for future rational drug design.

Acute Disease↗

PubMed2005

National and regional incidence of surgery for adult hydrocephalus in Sweden.

In Sweden, the annual incidence of surgery for hydrocephalus was 3.4 per 100,000 adults between the years 1996 and 1998. The most common indication for surgery was normal pressure hydrocephalus (NPH; 47%), followed by high-pressure hydrocephalus (27%). Seventy-three percent of the patients had communicating hydrocephalus, of which 63% had NPH. Twenty percent of the patients had non-communicating hydrocephalus, of which half resulted from aqueduct stenosis. The annual incidence of operations varied between regional clinics from 2.3 to 6.3 per 100,000 inhabitants.

Adolescent↗

PubMed2004

Telomere shortening and mitotic dysfunction generate cytogenetic heterogeneity in a subgroup of renal cell carcinomas.

Most renal cell carcinomas (RCC) show only simple chromosomal changes. However, a more complex cytogenetic pattern has been found in a subgroup of aggressive RCC, indicating that further accumulation of chromosome changes could play a role in tumour progression. To explore the possible mechanisms behind cytogenetic evolution in RCC, a parallel assessment of chromosome mutations and mitotic segregation pattern in eight tumours was performed. In the majority of cases, no abnormalities in the cell division machinery were found and the rate of alterations in chromosome copy number, as measured by interphase FISH, was similar to that in non-neoplastic cells. This was reflected by relatively simple karyotypes, with little cytogenetic intratumour heterogeneity. In contrast, another group of tumours exhibited several cytogenetically related clones with additional structural chromosomal changes at two or more ploidy levels and a frequency of copy number alterations that was higher than in normal cells. In these cases, the telomere repeat sequences were abnormally short and chromosomal breakage-fusion-bridge events were observed at cell division, as well as multipolar configurations and supernumerary centrosomes. Abnormalities of the cell division machinery may thus contribute to the evolution of complex karyotypes and genetic intratumour heterogeneity in a subgroup of RCC.

Adult↗

PubMed2003

More efficient mobilisation of peripheral blood stem cells with HiDAC+AMSA+G-CSF than with mini-ICE+G-CSF in patients with AML.

We have compared the efficacy of two PBSC mobilisation regimens, mini-ICE+filgrastim (second consolidation) and HiDAC+AMSA+filgrastim (third consolidation), in two consecutive cohorts of patients with AML CR1 receiving treatment according to a joint protocol. Group A: 18 patients, aged 41 (21-65) years, were mobilised with mini-ICE (idarubicin 8 mg/m(2)+cytarabine 800 mg/m(2)+etoposide 150 mg/m(2) days 1-3) followed by filgrastim 300-480 microg once daily s.c. from day 11 after start of chemotherapy. Only four patients reached >5 CD34+ cells/microl blood (B-CD34+) and were able to undergo leukaphereses. Two out of 18 (11%) reached the defined target of >/=2.0 x 10(6) CD34+ cells/kg after 1-3 leukaphereses. Group B: 20 patients, aged 50 (29-67) years, received HiDAC+AMSA (cytarabine 3 g/m(2) b.i.d. days 1, 3, 5+amsacrine 150 mg/m(2) q.d. days 2, 4) followed by filgrastim at a similar dose starting on day 7. A total of 18 patients reached B-CD34+ >5/microl and underwent PBSC harvesting, starting on day 23 (14-29) and yielding 4.0 (0.9-21) x 10(6) CD34+ cells/kg. Of 20 patients, 17 (85%) reached the defined target of >/=2.0 x 10(6) CD34+ cells/kg after 1-3 leukaphereses. We conclude that HiDAC+AMSA+G-CSF - in contrast to mini-ICE+G-CSF - is an efficient regimen for mobilising PBSC in patients with AML CR1.

Acute Disease↗

PubMed2002

Molecular cytogenetic mapping of recurrent chromosomal breakpoints in tenosynovial giant cell tumors.

Tenosynovial giant cell tumor (TGCT) is the most common benign tumor of synovium and tendon sheath. Cytogenetic data indicate that 1p11-13 is the region most frequently involved in structural rearrangements. With the aim of eventually identifying the genes associated with TGCT development, we have investigated 1p11-13 breakpoints using fluorescence in situ hybridization (FISH) analysis, with a panel of yeast artificial chromosome (YAC) probes covering 1p11-21. Twenty-six tumors were analyzed by G-banding, and 24 of these showed a breakpoint in 1p11-13. The cytogenetic findings add to previous observations that, among a variety of translocations involving 1p11-13, chromosome 2 is the most common translocation partner, with a breakpoint in 2q35-37. This aberration was found in eight cases. Other recurrent translocation partners, found in two or three cases, were 5q22-31, 11q11-12, and 8q21-22. Material from 21 tumors was available for FISH analysis, which revealed that the breakpoints clustered to one region spanned by two YAC probes, 914F6 and 885F12 located in 1p13.2, in 18 cases. Bacterial artificial chromosome probes were used to map the recurrent breakpoint on chromosome 2. In four of seven cases there was a breakpoint within the sequence covered by probe 260J21, where the RDC1 gene is located, a gene reported to fuse with HMGIC in lipomas with a 2;12 translocation.

Adolescent↗

PubMed2002

Acute myeloid leukemia with inv(16)(p13q22): involvement of cervical lymph nodes and tonsils is common and may be a negative prognostic sign.

Acute myeloid leukemia (AML) with inv(16)(p13q22) or the variant t(16;16)(p13;q22), is strongly associated with the FAB subtype M4Eo. A high incidence of CNS involvement was reported in the 1980s, but otherwise little is known about the pattern of extamedullary leukemia (EML) manifestations in this AML type. We have compiled clinical and cytogenetic data on 27 consecutive AML cases with inv(16)/t(16;16) from southern Sweden. In general, these AMLs displayed the clinical features that have previously been described as characteristic for this disease entity: low median age, hyperleukocytosis, M4Eo morphology, and a favorable prognosis. However, CNS leukemia was only seen in relapse in one patient diagnosed in 1980, whereas the most common EML manifestation in our series was lymphadenopathy (5/27, 19%), most often cervical with or without gross tonsillar enlargement. A review of previously published, clinically informative cases corroborates that lymphadenopathy, with preference for the cervical region, is the most common EML at diagnosis in inv(16)-positive AML (58/175, 33%). CNS leukemia, on the other hand, has been reported in only 17% of the cases, mostly in the relapse setting, with a diminishing frequency over time, possibly due to protective effects of high-dose cytarabine. Other reported EML sites include the scalp, ovaries, and the intestine. Cervicotonsillar EML was in our series associated with a shorter duration of first remission, (P < 0.05), and may hence prove to be an important clinical parameter when deciding treatment strategies in AML with inv(16)/t(16;16).

Adult↗

PubMed2002

Cytogenetic features of multiple myeloma: impact of gender, age, disease phase, culture time, and cytokine stimulation.

Relatively little is known about the cytogenetic features of multiple myeloma (MM) when compared to other hematologic malignancies. The reasons for this are most likely manifold, and include a low mitotic index of the malignant cells and the presence of cytogenetically cryptic abnormalities as well as of complex karyotypes with poor chromosome morphology. In the present study, we have investigated whether various culture conditions may influence the yield of abnormal metaphases in MM and, in the related plasma cell dyscrasias, monoclonal gammopathy of undetermined significance (MGUS) and plasmacytomas (PC). In addition, the possible impact of age, gender, and disease phase on the cytogenetic features has been analyzed. A total of 95 samples from 74 cases (68 MM, three PC, and three MGUS patients) were obtained for cytogenetic analysis. The samples were cultured either in conventional medium or in medium containing IL-6 and GM-CSF, and the culture times varied from 24 to 120 h. In total, 186 cultures were analyzed. Metaphase fluorescence in situ hybridization analysis using probes specific for 14q32, i.e. IGH rearrangements, could be performed in 57 of the 74 cases, and revealed 14q32 aberrations in 10 cases not seen by conventional G-banding. Abnormal karyotypes were detected in 77 (41%) of the 186 cultures, 46 (48%) of the 95 samples, and in 41 (55%) of the 74 patients, revealing a total of 20 chromosomal aberrations previously not reported in plasma cell dyscrasias. We found no evidence that gender, age, disease phase, culture time, or cytokine stimulation significantly influences the karyotypic features of MM.

Adult↗

PubMed2001

Identification of cytogenetic subgroups and karyotypic pathways in transitional cell carcinoma.

The clinical course in urinary bladder cancer is difficult or impossible to predict based on conventional disease parameters. It is a reasonable hypothesis that the genetic aberrations acquired by the tumor cells, being instrumental in bringing about the disease in the first place, may also hold the key to more reliable prognostication. However, though 200 transitional cell carcinomas (TCC), the most common bladder cancer in the Western world, with clonal chromosomal abnormalities have been reported, our knowledge about the karyotypic characteristics of these tumors remains insufficient. The aberration pattern is clearly nonrandom, but no completely specific primary or secondary karyotypic abnormality has been identified, and the chronological order in which the aberrations appear during disease progression is not well known. The high degree of karyotypic complexity in epithelial tumors like TCC is one reason why our picture of the sequential order of cytogenetic evolution is unclear. To overcome some of these difficulties we have used several statistical methods that allow analysis and interpretation of the relationship between cytogenetic aberrations in TCC. We show that there exists a temporal order with respect to the appearance of chromosomal imbalances and that this order is highly correlated with tumor stage and grade. Analyzing changes in the distribution of imbalances per tumor in G1, G2, and G3 tumors, we suggest that progression involves the acquisition of cytogenetically detectable and submicroscopic genetic changes at comparable frequencies. By means of computer simulations, we show that the imbalances -9, +7, and 1q+ appear earlier than expected from random events and that -6q, -5q, -18, +5p, -22p, and -15 appear later than expected. Using principal component analysis, we identify two cytogenetic pathways in TCC, one initiated by -9 and followed by -11p and 1q+, the other initiated by +7 and followed by 8p- and +8q. The -9 pathway was correlated with stage Ta-T2 tumors, whereas the +7 pathway was correlated with stage T1-T3 tumors, i.e., +7 tumors appeared to be more aggressive. Although these pathways are well separated at earlier stages, they later converge to contain a common set of imbalances.

Carcinoma, Transitional Cell↗

PubMed2001

Cytogenetic and fluorescence in situ hybridization characterization of chromosome 8 rearrangements in head and neck squamous cell carcinomas.

Structural rearrangements of chromosome 8 are frequently encountered in squamous cell carcinomas of the head and neck (HNSCC). These aberrations often affect the centromeric region, resulting in the formation of isochromosome i(8q) and whole arm translocations. Some tumors may display structural rearrangements of 8p23. To characterize further the localization of the breakpoints in such rearrangements, 12 HNSCC known to carry pericentromeric rearrangements of chromosome 8 and 8p23 abnormalities were investigated with fluorescence in situ hybridization (FISH) by the use of 15 YAC clones spanning 8p23 and 8p11 to 8q11. FISH confirmed that all, except one, aberrations cytogenetically interpreted to be i(8q) were true, monocentric i(8q). Similarly, all whole-arm translocations appeared as centric fusions. It could thus be concluded that the essential outcome of these rearrangements is genomic imbalances and not rearrangement of genes in the pericentromeric region. By the use of five YAC clones mapping to 8p23, different breakpoints at the molecular level were disclosed in cases with cytogenetically identical 8p23 rearrangements. An evaluation of the genomic imbalances detected in the present series revealed that overrepresentation of 8q material was present in 11 of the 12 tumors. The most commonly gained segment was 8q22 approximately qter, found in all cases with 8q overrepresentation. Loss of parts of or the entire 8p was seen in 10 tumors. The smallest overlapping deleted region was localized to the subtelomeric region of 8p.

Aged↗

PubMed2001

Telomere dysfunction triggers extensive DNA fragmentation and evolution of complex chromosome abnormalities in human malignant tumors.

Although mechanisms for chromosomal instability in tumors have been described in animal and in vitro models, little is known about these processes in man. To explore cytogenetic evolution in human tumors, chromosomal breakpoint profiles were constructed for 102 pancreatic carcinomas and 140 osteosarcomas, two tumor types characterized by extensive genomic instability. Cases with few chromosomal alterations showed a preferential clustering of breakpoints to the terminal bands, whereas tumors with many changes showed primarily interstitial and centromeric breakpoints. The terminal breakpoint frequency was negatively correlated to telomeric TTAGGG repeat length, and fluorescence in situ hybridization with telomeric TTAGGG probes consistently indicated shortened telomeres and >10% of chromosome ends lacking telomeric signals. Because telomeric dysfunction may lead to formation of unstable ring and dicentric chromosomes, mitotic figures were also evaluated. Anaphase bridges were found in all cases, and fluorescence in situ hybridization demonstrated extensive structural rearrangements of chromosomes, with terminal transferase detection showing fragmented DNA in 5-20% of interphase cells. Less than 2% of cells showed evidence of necrosis or apoptosis, and telomerase was expressed in the majority of cases. Telomeric dysfunction may thus trigger chromosomal fragmentation through persistent bridge-breakage events in pancreatic carcinomas and osteosarcomas, leading to a continuous reorganization of the tumor genome. Telomerase expression is not sufficient for completely stabilizing the chromosome complement but may be crucial for preventing complete genomic deterioration and maintaining cellular survival.

Adolescent↗

PubMed2001

[Incidence of surgery for hydrocephalus in adults surveyed: same number afflicted by hydrocephalus as by multiple sclerosis].

The incidence of surgical treatment for adult hydrocephalus (older than 18 years) in Sweden from 1996 to 1998 was surveyed. The number of operations was 891 and the average incidence 3.36 operations per 100,000 inhabitants and year, varying regionally from 2.3 to 6.3. The mean age was 60 years (range 18-92), with no sex difference. Normal pressure hydrocephalus (47%) was most common, followed by communicating high pressure hydrocephalus (27%) and aqueductal stenosis (11%). 804 shunt operations (90%) and 67 ventriculostomies (7.5%) were performed, 2% were unclassified.

Adult↗

PubMed2001

Multivariate analyses of genomic imbalances in solid tumors reveal distinct and converging pathways of karyotypic evolution.

A total of 3,016 malignant solid tumors (kidney, colorectal, breast, head and neck, ovarian, and lung carcinomas, neuroglial tumors, malignant melanoma, and testicular germ cell tumors) were selected for statistical analyses regarding karyotypic evolution. Genomic imbalances, i.e., net gains and losses, present in more than 5% of each tumor type were identified. Individual tumors were then classified with respect to absence or presence of these imbalances. To analyze for possible patterns of correlated imbalances, principal component analyses (PCA) were performed. Furthermore, algorithms were developed to analyze the temporal order of the imbalances, as well as the possible selection for early or late appearance in the karyotypic evolution. By analyzing the temporal order of imbalances common to many tumor types, a general order for nine of these emerged, namely, +7, -3p, -6q, -1p, -8p, -17p, -9p, -18, and -22. The distributions of the number of imbalances per case revealed a geometrical distribution, ranging from one to nine imbalances per tumor, in the majority of the tumor types. In tumor types in which cases with a high number of imbalances per case were frequent, notably head and neck, ovarian, and lung carcinomas, the overall distributions were bimodal, indicating the presence of two modes of chromosome evolution. By combining data from the PCA with the temporal analyses, it was possible to identify karyotypic pathways. It was found that the majority of the tumor types displayed more than one cytogenetic route, but, as the karyotypic evolution continued, these converged to a common pathway.

Allelic Imbalance↗

PubMed2001

Abnormal nuclear shape in solid tumors reflects mitotic instability.

Abnormalities in nuclear morphology are frequently observed in malignant tissues but the mechanisms behind these phenomena are still poorly understood. In this study, the relation between abnormal nuclear shape and chromosomal instability was explored in short-term tumor cell cultures. Mitotically unstable ring and dicentric chromosomes were identified by fluorescence in situ hybridization at metaphase and subsequently localized in interphase nuclei from five malignant soft tissue tumors. The vast majority (71 to 86%) of nuclear blebs, chromatin strings, and micronuclei contained material from the unstable chromosomes, whereas few (<11%) were positive for stable chromosomes. Nuclear morphology was also evaluated in fibroblasts and an osteosarcoma cell line exposed to irradiation. A linear correlation was found between the frequency of abnormalities in nuclear shape, on one hand, and cells with unstable chromosomes (r = 0.87) and anaphase bridge configurations (r = 0.98), on the other hand. The relation between nuclear shape and karyotypic pattern was investigated further in cultures from 58 tumors of bone, soft tissue, and epithelium. Blebs, strings, and micronuclei were significantly more frequent in tumors that contained rings, dicentrics, or telomeric associations than in those exhibiting only stable aberrations (P: < 0.001) and a positive correlation (r = 0.78) was found between the frequency of such nuclear abnormalities and the intratumor heterogeneity of structural chromosome aberrations. These results indicate that the formation of nuclear blebs, chromatin strings, and micronuclei in malignant tissues is closely related to the breakage-fusion-bridge type of mitotic disturbances. Abnormalities in nuclear shape may thus primarily be regarded as an indicator of genetic instability and intratumor heterogeneity, independent of cytogenetic complexity and the grade of malignancy.

Cell Line↗

PubMed2001

Extensive cytogenetic heterogeneity in a benign retroperitoneal schwannoma.

A benign retroperitoneal schwannoma from a patient without prior exposure to radiotherapy or chemotherapy was analyzed by chromosome banding after short-term culture. An extensive intratumor heterogeneity in the form of 29 karyotypically related as well as unrelated clones was found. The aberrant clones were diploid or near-diploid and displayed both numerical and structural changes. All chromosomes, except 11, 16, and 20, were affected. Numerical changes included trisomies X, 7, 9, 17, and 18, and monosomies 13 and 18. No clonal loss of chromosome 22, the most characteristic abnormality in schwannomas of other locations, was, however, detected. The structural aberrations resulted in a total of 58 chromosomal breakpoints, with chromosomes 18, 1, and 15 participating in rearrangements most frequently, followed by chromosomes 14, 2, and 22. A striking finding was the clonal involvement of 18p11 in eight rearrangements affecting different chromosomes, suggesting alteration of telomeric function. The molecular mechanisms underlying the observed massive polyclonality in the schwannoma, particularly the presence of cytogenetically unrelated clones, are unknown and probably heterogeneous.

Aged↗