Cytogenetic t(11;17)(q13;q21) in a pediatric ependymoma. Is 11q13 a recurring breakpoint in ependymomas?

Mutation profiling of anaplastic ependymoma grade III by Ion Proton next generation DNA sequencing

Background: Ependymomas are glial tumors derived from differentiated ependymal cells. In contrast to other types of brain tumors, histological grading is not a good prognostic marker for these tumors. In order to determine genomic changes in an anaplastic ependymoma, we analyzed its mutation patterns by next generation sequencing (NGS). Methods:  Tumor DNA was sequenced using an Ion PI v3 chip on Ion Proton instrument and the data were analyzed by Ion Reporter 5.6. Results: NGS analysis identified 19 variants, of which four were previously reported missense variants; c.395G>A in IDH1, c.1173A>G in PIK3CA, c.1416A>T in KDR and c.215C>G in TP53. The frequencies of the three missense mutations ( PIK3CA c.1173A>G, KDR c.1416A>T, TP53, c.215C>G) were high, suggesting that these are germline variants, whereas the IDH1 variant frequency was low (4.81%). However, based on its FATHMM score of 0.94, only the IDH1 variant is pathogenic; other variants TP53, PIK3CA and KDR had FATHMM scores of 0.22, 0.56 and 0.07, respectively. Eight synonymous mutations were found in FGFR3, PDGFRA, EGFR, RET, HRAS, FLT3, APC and SMAD4 genes. The mutation in FLT3 p.(Val592Val) was the only novel variant found. Additionally, two known intronic variants in KDR were found and intronic variants were also found in ERBB4 and PIK3CA. A known splice site mutation at an acceptor site in FLT3, a 3'-UTR variant in the CSF1R gene and a 5'_UTR variant in the SMARCB1 gene were also identified. The p-values were below 0.00001 for all variants and the average coverage for all variants was around 2000x. Conclusions: In this grade III ependymoma, one novel synonymous mutation and one deleterious missense mutation is reported. Many of the variants reported here have not been detected in ependymal tumors by NGS analysis previously and we therefore report these variants in brain tissue for the first time.

Mutation profiling of anaplastic ependymoma grade III by Ion Proton next generation DNA sequencing

Background: Ependymomas are glial tumors derived from differentiated ependymal cells. In contrast to other types of brain tumors, histological grading is not a good prognostic marker for these tumors. In order to determine genomic changes in an anaplastic ependymoma, we analyzed its mutation patterns by next generation sequencing (NGS). Methods:  Tumor DNA was sequenced using an Ion PI v3 chip on Ion Proton instrument and the data were analyzed by Ion Reporter 5.6. Results: NGS analysis identified 19 variants, of which four were previously reported missense variants; c.395G>A in IDH1, c.1173A>G in PIK3CA, c.1416A>T in KDR and c.215C>G in TP53. The frequencies of the three missense mutations ( PIK3CA c.1173A>G, KDR c.1416A>T, TP53, c.215C>G) were high, suggesting that these are germline variants, whereas the IDH1 variant frequency was low (4.81%). However, based on its FATHMM score of 0.94, only the IDH1 variant is pathogenic; other variants TP53, PIK3CA and KDR had FATHMM scores of 0.22, 0.56 and 0.07, respectively. Eight synonymous mutations were found in FGFR3, PDGFRA, EGFR, RET, HRAS, FLT3, APC and SMAD4 genes. The mutation in FLT3 p.(Val592Val) was the only novel variant found. Additionally, two known intronic variants in KDR were found and intronic variants were also found in ERBB4 and PIK3CA. A known splice site mutation at an acceptor site in FLT3, a 3'-UTR variant in the CSF1R gene and a 5'_UTR variant in the SMARCB1 gene were also identified. The p-values were below 0.00001 for all variants and the average coverage for all variants was around 2000x. Conclusions: In this grade III ependymoma, one novel synonymous mutation and one deleterious missense mutation is reported. Many of the variants reported here have not been detected in ependymal tumors by NGS analysis previously and we therefore report these variants in brain tissue for the first time.

Spinal cord ependymomas and the appearance of other de novo tumors: a systematic review

Introduction

Ependymomas are rare glial tumors of the brain representing less than 5% of brain tumors. However, spinal cord ependymomas in adults account for over 60% of all ependymomas including those arising from the filum terminale and only 40% are intracranial. Reports of the appearance of another neoplasia at a different location in patients with spinal ependymoma are scarce.

Methods

We searched PubMed for studies related to spinal cord ependymomas published over the last 30 years (from January 1984) and retrieved 1197.

Results

We identified only two studies that met our criteria and we found an incidence of 9% of secondary neoplasias after treatment for spinal ependymoma. The neoplasms were diagnosed from 2 months to 20 years after patients underwent surgery for intraspinal ependymoma. These included pancreatic cancer, prostate cancer, Hodgkin lymphoma, intracranial meningioma, mucin-producing pulmonary adenocarcinoma, gastric cancer and astrocytoma.

Conclusions

The genetic abnormalities affecting patients with spinal ependymomas may indicate a predisposition to the development of secondary cancers or a general failure of the repairing mechanism in their DNA. The unaffected survival rates in those individuals permit for a long period the accumulation of different mutations on the genome and thus the appearance of a second cancer. However, more studies are needed, particularly in young patients with high survival rates.

Tanycytic ependymoma of the filum terminale associated with multiple endocrine neoplasia type 1: first reported case

BACKGROUND CONTEXT

Ependymoma associated with multiple endocrine neoplasia type 1 (MEN-1) is an extremely rare clinical entity. To the best of our knowledge, only five cases of ependymoma associated with MEN-1 have been previously described. Furthermore, there has been no case of tanycytic ependymoma of the filum terminale associated with MEN-1.

PURPOSE

The present case report illustrates a 53-year-old man with tanycytic ependymoma of the filum terminale associated with MEN-1. We review the literature on ependymoma with MEN-1 and tanycytic ependymoma of the cauda equina region and also discuss the risk of recurrence.

STUDY DESIGN

A case report.

METHODS

The patient presented with complaints of nocturnal pain in the lower back, accompanied by numbness around the anus and intermittent claudication for approximately 1 year. Magnetic resonance imaging (MRI) identified an intradural-enhancing, large mass lesion at the level from Th12 to L2 vertebrae, with a cranial cystic lesion.

RESULTS

Open-door laminoplasty of the Th12, L1, and L2 and en bloc tumor resection with thickened filum terminale were performed. Histopathologic examination of the tumor specimens showed tanycytic ependymoma (World Health Organization Classification Grade II). At the time of the 2-year and 8-month follow-up examination, MRI did not show tumor recurrence.

CONCLUSIONS

This is the first reported case of this clinical entity. A careful follow-up of patients with this unusual tumor is strongly recommended.

Loss of chromosome 1 in myxopapillary ependymoma suggests a region out of chromosome 22 as critical for tumour biology: a FISH analysis of four cases on touch imprint smears

OBJECTIVE

Ependymomas are glial tumours. They constitute approximately 5-10% of intracranial tumours and are tumours which can recur. Predictive factors of outcome in ependymomas are not well established. Karyotypic studies are relatively scarce and loss of chromosome 22 has been described to correlate with recurrence. We are unaware of any reports involving chromosome 1 aberrations in the malignant progression of ependymomas.

METHODS

Cytogenetic analysis of four myxopapillary ependymomas was performed using double target fluorescent in situ hybridization (FISH), focusing on chromosomes 1 and 22.

RESULTS

One patient's tumour had recurred. FISH was performed on 500 nuclei/tumours. All four cases showed a loss of chromosome 22q while only one showed an additional loss of chromosome 1p, and this was the one that recurred.

CONCLUSIONS

We support the presence of a tumour suppressor gene on 1p associated with relapse in myxopapillary ependymomas and suggest that status of chromosome 1p by FISH may indicate a high-risk group of patients harbouring this tumour. More studies of this type are needed towards this direction as our results refer to a minimal number of individuals analysed.

Low frequency of chromosomal imbalances in anaplastic ependymomas as detected by comparative genomic hybridization

We screened 26 ependymomas in 22 patients (7 WHO grade I, myxopapillary, myE; 6 WHO grade II, E; 13 WHO grade III, anaplastic, aE) using comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). 25 out of 26 tumors showed chromosomal imbalances on CGH analysis. The chromosomal region most frequently affected by losses of genomic material clustered on 13q (9/26). 6/7 myE showed a loss on 13q14-q31. Other chromosomes affected by genomic losses were 6q (5/26), 4q (5/26), 10 (5/26), and 2q (4/26). The most consistent chromosomal abnormality in ependymomas so far reported, is monosomy 22 or structural abnormality 22q, identified in approximately one third of Giemsa-banded cases with abnormal karyotypes. Using FISH, loss or monosomy 22q was detected in small subpopulations of tumor cells in 36% of cases. The most frequent gains involved chromosome arms 17 (8/26), 9q (7/26), 20q (7/26), and 22q (6/26). Gains on 1q were found exclusively in pediatric ependymomas (5/10). Using FISH, MYCN proto-oncogene DNA amplifications mapped to 2p23-p24 were found in 2 spinal ependymomas of adults. On average, myE demonstrated 9.14, E 5.33, and aE 1.77 gains and/or losses on different chromosomes per tumor using CGH. Thus, and quite paradoxically, in ependymomas, a high frequency of imbalanced chromosomal regions as revealed by CGH does not indicate a high WHO grade of the tumor but is more frequent in grade I tumors.

Familial intracranial ependymomas. Report of three cases in a family and review of the literature

Familial cases of intracranial ependymomas have been well documented in the literature. The authors present two cases from a family in which three members harbored intracranial ependymomas. A 54-year-old man with fourth ventricular ependymoma underwent resection of the tumor followed by radiation therapy. His son presented at age 36 years with a fourth ventricular tanycytic ependymoma and underwent total resection of the ependymoma with postoperative radiation therapy. The father's sister had been treated at another institution for a posterior fossa ependymoma.The association of ependymomas with molecular genetic alterations in chromosome 22 has been previously described. Further investigation of the genetic influences may lead to better therapeutic approaches for this relatively rare clinicopathological entity.

A family with spinal anaplastic ependymoma: evidence of loss of chromosome 22q in tumor

Familial ependymal tumors are a very rare disease, the pathogenesis of which is unknown. Previous studies indicate an involvement of tumor suppressor genes localized within chromosomal region 22q, whereas details are still unclear. Here we report a non-neurofibromatosis type-2 (non-NF2) Japanese family in which two of the four members are affected with cervical spinal cord ependymoma, and one of the four is affected with schwannoma. Loss of heterozygosity (LOH) studies were carried out searching for common allelic loss at chromosomal region 22q11.2-qtel in two of the affected patients. Our findings support a prediction for existence of a tumor suppressor gene on chromosome 22 especially related to the tumorigenesis of familial ependymal tumors.

Complex cytogenetic abnormalities including telomeric associations and MEN1 mutation in a pediatric ependymoma

Ependymomas are neuroectodermal tumors of the brain and spinal cord. Some recurrent cytogenetic aberrations have been reported in these tumors, including alterations involving chromosomes 22, 6, and 11. However, consistent molecular alterations have not been identified in ependymal tumors. We studied a recurrent ependymoma in a 3-year-old patient by standard cytogenetic and molecular analysis of TP53 and MEN1 genes. In the present case, we found many of the cytogenetic features previously described as being recurrent in ependymomas, including unstable telomeric alterations. Furthermore, we detected a novel acquired heterozygous mutation in the MEN1 gene. The chromosomal instability produced by the telomeric alterations and the mutation in the MEN1 gene could be important events in the tumorigenesis of ependymomas.

Molecular genetic alterations on chromosomes 11 and 22 in ependymomas

Ependymomas arise from the ependymal cells at different locations throughout the brain and spinal cord. These tumors have a broad age distribution with a range from less than 1 year to more than 80 years. In some intramedullary spinal ependymomas, mutations in the neurofibromatosis 2 (NF2) gene and loss of heterozygosity (LOH) on chromosome arm 22q have been described. Cytogenetic studies have also identified alterations involving chromosome arm 11q, including rearrangements at 11q13, in ependymomas. We analyzed 21 intramedullary spinal, 14 ventricular, 11 filum terminale and 6 intracerebral ependymomas for mutations in the MEN1 gene, which is located at 11q13, and mutations in the NF2 gene, which is located at 22q12, as well as for LOH on 11q and 22q. NF2 mutations were found in 6 tumors, all of which were intramedullary spinal and all of which displayed LOH 22q. Allelic loss on 22q was found in 20 cases and was significantly more frequent in intramedullary spinal ependymomas than in tumors in other locations. LOH 11q was found in 7 patients and exhibited a highly significant inverse association with LOH 22q (p<0.001). A hemizygous MEN1 mutation was identified in 3 tumors, all of which were recurrences from the same patient. Interestingly, the initial tumor corresponded to WHO grade II and displayed LOH 11q but not yet a MEN1 mutation. In 2 subsequent recurrences, the tumor had progressed to anaplastic ependymoma (WHO grade III) and exhibited a nonsense mutation in exon 10 of MEN1 (W471X) in conjunction with LOH 11q. This suggests that loss of wild-type MEN1 may be involved in the malignant progression of a subset of ependymomas. To conclude, our findings provide evidence for different genetic pathways involved in ependymoma formation and progression, which may allow to define genetically and clinically distinct tumor entities.

Cytogenetic study of 33 ependymomas

Ependymomas are glial tumors. They constitute approximately 5-10% of intracranial tumors. Ependymomas are tumors which can recur. Predictive factors of outcome in ependymomas are not well-established. Karyotypic studies on ependymomas are relatively scarce, and no specific chromosomal change has been described in these neoplasms. We performed a cytogenetic study of 33 ependymomas, of which eight were recurrent tumors, to determine the type and incidence of cytogenetic changes.

Karyotype studies in 18 ependymomas with literature review of 107 cases

Cytogenetic studies from 17 pediatric ependymomas and 1 ependymoblastoma are presented. Eight tumors had abnormal karyotypes. Another 107 published cases of cytogenetic analyses from pediatric and adult ependymomas or ependymoblastomas were reviewed. Of the total 125 tumors, 83 (66%) had abnormal karyotypes, of which 24 had a sole autosomal abnormality. Approximately one third had monosomy 22 (-22) or breakpoint 22q11-13, with a higher incidence in adult (56%) versus pediatric (28%) tumors. Structural abnormalities of chromosomes 1, 6, and 17, and numerical abnormalities of 7, 9, 12, and 20, in particular, are also discussed. Although no primary cytogenetic abnormality is evident, these findings may provide direction for additional investigations regarding the classification of these tumors.

Clonal telomeric fusions and chromosome instability in a subcutaneous sacrococcygeal myxopapillary ependymoma

Subcutaneous sacrococcygeal myxopapillary ependymoma (SSME) is a very rare neurologic tumor with no demonstrable connection to the spinal column. Little is known of its etiology, clinical characteristics, or cytogenetics. Giemsa-band analysis revealed a stemline karyotype showing 62 chromosomes. Sidelines within the tumor showed clonal telomeric fusions resulting in dicentric chromosomes involving the fusion of numerous chromosomes. Recurrent telomeric fusions resulted in the progressive deletion of chromosome bands 11q25 and 11q23 and subsequently the entire long arm. This is the first case of a SSME to show clonal cytogenetic aberrations. However, of greater interest is the demonstration of the clonal progression of telomeric fusions resulting in dicentric chromosomes and the subsequent loss of chromosome arms. The observation of clonal telomeric breakage/fusion cycles as progenitor lesions to subsequent deletions provides evidence for telomeric association as an intermediate step in the progression of chromosomal instability.

The molecular biology of ependymomas

Intracranial ependymomas are the third most common primary brain tumor in the pediatric population. Although an anaplastic variant is recognized, numerous studies examining the prognostic implications of histological features, such as necrosis, endothelial proliferation and mitoses, have yielded contradictory results. In order to improve outcome prediction in affected patients and to refine therapeutic decision-making, there is a strong need for identifying relevant biological correlates of tumor behavior. The molecular biology of tumors is a rapidly expanding field and includes investigations into cytogenetics, oncogenes, growth factors, growth factor receptors, hormonal receptors, proliferation markers, apoptosis, cell cycle genes and cell adhesion molecules, as well as factors potentially related to therapeutic resistance, such as the multidrug resistance gene. The molecular biology of astrocytic tumors in adults has been the subject of many studies; however, relatively few studies have been focused on ependymomas. Herein we review potential oncological markers in ependymomas that have been identified to date and highlight the limitations of our current knowledge as a basis for defining areas for future investigation.

Cytogenetics of pediatric central nervous system tumors

A cytogenetic analysis was performed on short-term cultures of 43 previously untreated childhood central nervous system neoplasms of various histology. The cells were obtained from pediatric patients, none of whom had received therapy before karyotypic evaluation. Successful chromosome studies were performed on 24 tumors. The most commonly detected structural abnormalities involved chromosomes 1 and 17. Other structural chromosome abnormalities involved chromosomes 3, 6, 8, 9, 11, 12, and 20.

Molecular genetic analysis of chromosome arm 17p and chromosome arm 22q DNA sequences in sporadic pediatric ependymomas

Ependymomas are glial tumors of the brain and spinal cord occurring both sporadically and in a familial syndrome, neurofibromatosis type 2 (NF2). Previous analyses performed on specimens obtained predominantly from adult patients have shown loss of DNA sequences from chromosome arm 22q, which is the location of the NF2 gene. Previously, we documented the consistent loss of chromosome arm 17p DNA in medulloblastoma and astrocytoma, which are the most common brain tumors in children. Although mutation of the TP53 gene located on 17p is the most frequent genetic mutation in all adult tumor types, such mutations are rare in most childhood brain tumors investigated to date. We studied a series of pediatric ependymoma specimens (16 intracranial and 2 spinal) for loss of 17p and 22q DNA sequences and for mutation of the TP53 and NF2 genes. None of the children had the clinical stigmata of NF2. We detected loss of 17p DNA sequences in 9 of the 18 specimens (50%); in 7 of 9 of these specimens (78%), the 144-D6 marker was deleted. In contrast, only 2 of these same 18 specimens (11%) showed loss of 22q DNA. One TP53 gene mutation was detected in a child from a cancer kindred. No mutations were detected in the NF2 gene. Our results suggest that loss of chromosome arm 17p DNA sequences is common in sporadic pediatric ependymomas and that, in contrast to ependymomas in adults, deletion of chromosome arm 22q sequences is rare. Furthermore, TP53 and NF2 gene mutations do not play an important role in the etiology of sporadic pediatric ependymomas.

Molecular biology of pediatric gliomas

The genes involved in the genesis and progression of adult astrocytic tumors have been an area of considerable investigation. The tumor suppressor gene, p53, has been implicated, as has the epidermal growth factor receptor gene. Additional currently unidentified genes lie on chromosomes 10 and 19. Interestingly, work on pediatric astrocytomas suggests that the genes involved are different. p53 is rarely mutated in pediatric tumors, the epidermal growth factor receptor gene is rarely amplified or mutated, and chromosome 10 deletions are rare. The only pediatric tumor that seems to mimic the findings in adult tumors is brainstem glioma, perhaps explaining the uniformly grim prognosis in this type of tumor. In the pilocytic astrocytoma of childhood, mutations in the neurofibromatosis type I gene have been implicated in tumor development. In this review, the oncogenesis of pediatric gliomas is discussed and compared and contrasted to what is known about tumors.

Exon scanning for mutations of the NF2 gene in pediatric ependymomas, rhabdoid tumors and meningiomas

Deletions of chromosome 22 have been identified in 3 types of childhood primary brain tumor: meningiomas, rhabdoid or atypical teratoid tumors (ATT) and ependymomas. This implicates the involvement of tumor suppressor genes on chromosome 22 in the genesis of these rare tumors. One such candidate tumor suppressor gene is the recently cloned neurofibromatosis 2 (NF2) locus. The purpose of our study was to determine the frequency of germ-line and somatic NF2 mutations in a selected group of brain tumors in children. Using single-strand conformation polymorphism (SSCP) assays we screened 17 exons of the NF2 gene in 13 pediatric brain tumors and 9 matched normal blood DNA samples. Tumors included 3 meningiomas, 2 rhabdoid or ATTs, 7 ependymomas and 1 malignant tumor of glial lineage. In addition, lymphoblastoid cell lines from 3 patients with rhabdoid/ATT in whom no tumor tissue was available were analyzed for germ-line mutations. Migration shifts were not detected in any of the normal DNA samples analyzed. Of the 13 tumors screened by SSCP, 1 meningioma with monosomy 22 produced a migration shift in exon 13. DNA sequencing of exon 13 revealed a deletion of a single guanine nucleotide (base 1397) in codon 466, causing a frame shift. While not all mutations might have been picked up by this technique, the data suggest that, similar to adult sporadic meningiomas, some pediatric meningiomas may result from somatic mutations in the NF2 gene. For rhabdoid tumors and ependymomas it appears that a locus distinct from NF2 might be responsible for tumorigenesis.

Recurrent anaplastic ependymoma with an abnormal karyotype and c-myc proto-oncogene overexpression

Cytogenetic analysis on a supratentorial, recurrent, anaplastic ependymoma from a 29-year-old female disclosed the presence of an abnormal clone with the karyotype 46,XX,der(8)t(8;11)(q24;p11),-11,add(?)t(?;11)(?;q13). By the Northern hybridization assay and immunohistochemical staining, tumor cells revealed overexpression of c-myc proto-oncogene, although no evidence of amplification or structural rearrangement of this gene was found.

Involvement of chromosome 22 in ependymomas

We have karyotyped a total of twelve ependymomas using GTG-banding including seven for which preliminary results have already been published. One case showing hyperdiploid main line with two marker chromosomes was further analyzed by nonisotopic chromosome in situ suppression hybridization. It was shown that the marker chromosomes consisted of 1q, 14q and 1q, and 22q. The possible role of chromosome 22 in ependymomas and the usefulness of fluorescence in situ hybridization for cytogenetic analysis in tumor investigation are discussed.

Chromosome aberrations in four ependymomas

Cytogenetic analysis of short-term cultures from three untreated and one recurrent ependymoma revealed clonal aberrations in three of the four tumors. A posterior fossa ependymoma from a 3-year-old male patient showed trisomy 11 as the sole clonal chromosome aberration. A recurrent spinal ependymoma from a 35-year-old male showed hypertriploid clones with abnormalities involving chromosomes 1p11,7q21, and 10p13. A 62-year-old male patient with a cerebellar ependymoma showed a hypodiploid stem-cell line with clonal structural aberrations of both the long and short arms of chromosome 1, an interstitial deletion of 2q, trisomy 7, and monosomy for chromosomes 11, 13, and 16. A 3-year-old female patient with posterior fossa ependymoma showed a normal 46,XX karyotype. Chromosome 1 aberrations appear to be the most consistent finding in this small series of tumors, with the net loss or rearrangement of chromosome 1 pter-->p22 material from two of the four tumors. These findings, in addition to a previously published case [1], suggest a possible role for genes on the short arm of chromosome 1 in the cytogenetic evaluation of ependymomas.

Multiple loci on human chromosome 11 control tumorigenicity of BK virus transformed cells

BK virus (BKV) is a human papovavirus that readily transforms rodent cells, but not human cells, to a neoplastic phenotype, suggesting that tumor-suppressor functions expressed in human cells control BKV oncogenicity. Transfer of a normal human chromosome 11 to BKV-transformed mouse cells suppresses the malignant phenotype. In this report we map the regions of chromosome 11 involved in tumor suppression. Transfer of chromosome 11 to the BKV-transformed hamster cell line HKBK produces monochromosomic hybrids retaining only portions of the transferred human chromosome. We have compared the tumorigenicity of the hybrids with the molecular mapping of chromosome 11 retained regions. This analysis indicated that 3 regions of human chromosome 11, 11p15.5, 11p13 and 11q13, cooperate in tumor suppression. However, 11q13 seems the most important, since all the HKBK/H11-induced tumors analysed had lost this region, whereas 11p15.5 and 11p13 were sometimes retained. The chromosomal regions identified in this study are deleted in several types of human tumors, suggesting that the BKV transformation system specifically detects tumor-suppressor genes on chromosome 11 that are involved in human oncogenesis. This model may be of use in isolating and cloning such genes. The results of this report raise the possibility that BKV may have a synergistic tumorigenic effect in human cells where tumor-suppressor genes controlling its oncogenic potential are inactivated.

Genetic aberrations in human brain tumors

Over the last decade, much has been learned about the genetic changes that occur in human neoplasia and how they contribute to the neoplastic state. Oncogenes and tumor suppressor genes have been identified, and many powerful molecular genetic techniques have emerged. Brain tumors have been intensively studied as part of this process. Specific and recurring genetic alterations have been identified and are associated with specific tumor types. In astrocytomas, for example, losses of genetic material on chromosomes 10 and 17 and amplification of the epidermal growth factor receptor gene seem important in pathogenesis, with the loss of chromosome 10 and the amplification of epidermal growth factor receptor being strongly associated with glioblastoma multiforme. Meningiomas, on the other hand, have usually lost part or all of chromosome 22. Brain tumors also express growth factors and growth factor receptors that may be important in promoting tumor growth and angiogenesis. These include epidermal growth factor, transforming growth factor-alpha, platelet-derived growth factor, the fibroblast growth factors, and vascular endothelial growth factor. In this article, we review the genetic aberrations that occur in the major types of brain tumors, including glial tumors, meningiomas, acoustic neuromas, medulloblastomas, primitive neuroectodermal tumors, and pituitary tumors. Wherever possible, clinical correlations have been made concerning the prognostic and therapeutic implications of specific aberrations. We also provide some background about the cytogenetic and molecular genetic techniques that have contributed to the description and understanding of these alterations and speculate as to some clinical and basic science issues that might be explored in the future.

The folate receptor in central nervous system malignancies of childhood

The folate receptor is a membrane linked glycoprotein that participates in the cellular accumulation of 5-methyltetrahydrofolic acid, methotrexate and 5,10-dideazatetrahydrofolic acid. Relative receptor overexpression has been observed in several malignant cell lines and tissues. In this study we determined receptor expression using western blot analysis in primary pediatric malignancies involving the central nervous system. This study suggests that ependymoma tumors have a high frequency of receptor expression which may reflect a specific cytogenetic abnormality or the cellular origin of these tumors. The potential role in developing selective chemotherapy mediated by the folate receptor is also discussed.

Involvement of 10q22 and 11q13 in hibernoma

A hibernoma studied cytogenetically had the karyotype 46,XY,t(9;10;11)(q34;q22;q13),t(17;19) (q21.3;q13). The findings are discussed and compared with those of the previous case described in the literature.