Genetic aberrations in gliomatosis cerebri support monoclonal tumorigenesis

Gliomatosis cerebri is a rare condition in which the brain is infiltrated by an exceptionally diffusely growing glial cell population involving at least 2 lobes, though often more extensive, sometimes even affecting infratentorial regions. The neoplastic proliferation may have a monoclonal origin, or alternatively, reflect progressive neoplastic change of an entire tissue field ("field cancerization"). The presence of an identical set of genetic aberrations throughout the lesion would point to monoclonality of the proliferation. In contrast, the finding of non-identical genetic changes in widely separated regions within the neoplasm would support the concept of field cancerization. In the present study, a unique autopsy case of gliomatosis was available to verify either one of these hypotheses. Tissue samples were randomly taken from 24 locations throughout the brain and used for genetic investigation. In all samples the histology showed an identical picture of slightly elongated astrocytic cells, typical for gliomatosis. TP53 exon 5-8 mutation analysis was performed on all samples. Genome-wide screening for chromosomal aberrations was accomplished by comparative genomic hybridization (CGH). In addition, loss of heterozygosity analysis for polymorphic markers on chromosomal regions of the 2 most frequently observed DNA deletions was carried out. The most widespread genetic aberration was mutation of exon 7 of TP53, which was detected in 20 of 24 samples. Bidirectional sequencing revealed a mutation in codon 234 (TAC234TGC), resulting in an amino acid substitution Tyr-Cys. CGH analysis revealed losses on 2q11-q31 in 13 of 24 samples and losses on 19q13-qter in 10 of 24 samples from both left and right hemispheres. Allelic imbalances for markers on 2q (2q14.3 and 2q22.1) and 19q (both 19q13.2) were demonstrated in 10 of 24 and 18 of 24 samples, respectively. Other widespread chromosomal aberrations included losses on 3q13-qter and 16q22-qter and gains on 7q22-qter. The wide distribution of a particular set of genetic aberrations in this case supports the concept of monoclonal tumor proliferation. The results point to involvement of TP53 mutation in the tumorigenesis of gliomatosis cerebri.     

Genetic characterisation of granular cell tumours

Seven granular cell tumours (GCT) were studied by comparative genomic hybridisation. These consisted of two cerebral and one pituitary GCT as well as four other central nervous system tumours predominantly composed of granular cells (one glioblastoma, meningioma, ganglioglioma and neurinoma each). DNA copy number changes were found in four of seven tumours. Overall, losses (mean: 1.0 per tumour) were more frequent than gains (mean: 0.6 per tumour) and no high-level gains were found. The only DNA copy number change found in two tumours (both cerebral GCT) was loss of 13q21, while the other nine aberrations were only encountered once each: the granular cells of one cerebral GCT additionally showed +1p32-pter, +9q33-qter, +20q, -4, and -18q, of the glioblastoma +7 and -10, and of the meningioma -1p and -22q, while the pituitary GCT, the ganglioglioma and the neurinoma showed no imbalances. Our data suggest that a variety of genetic changes are associated with granular cell formation and support the notion that GCT are not a distinct tumour entity characterised by specific chromosomal imbalances but rather a degenerative phenomenon of cells of various origin showing DNA copy number changes akin to the underlying tumour.     

α-Internexin in the diagnosis of oligodendroglial tumors and association with 1p/19q status

α-Internexin (INA) has been proposed to be a surrogate marker for the 1p/19q codeletion in oligodendroglial tumors (OTs). We analyzed INA expression in 83 glioma and 21 oligodendroglial phenotype-mimicking tumors (OMT) to assess its usefulness in differential diagnosis and its correlation with 1p/19q status; in particular, INA expression in gliomas with isolated/partial 1p or 19q deletions was assessed. α-Internexin expression and 1p/19q codeletion were present in 92% (34/37) of codeleted tumors (p < 0.0001). By contrast, INA was found in only 20% of cases with isolated/partial 1p aberrations and 36% of cases without 1p/19q deletions; it was also foundin 63% (10/16) of cases with isolated/partial 19q aberrations. α-Internexin expression was more specific in high-grade than in low-grade gliomas (66% vs 31%). Notably, a subset of tumors (10/83) displayed a biphasic INA expression pattern that was significantly associated with proliferation rate, whereas all areas harbored the 1p/19q codeletion. Only no or weak INA expression was seen in OMTs. In summary, INA is a useful marker to differentiate OTs from astrocytic tumors and OMTs, but INA expression is not exclusively linked to OTs harboring the 1p/19q codeletion. Moreover, it can sometimes be heterogeneously distributed within tumors, which emphasizes the need for 1p/19q analysis by molecular genetic techniques for diagnosis.     

Identification of subgroups of high-grade oligodendroglial tumors by comparative genomic hybridization.

In contrast to astrocytic tumors, approximately two thirds of anaplastic oligodendrogliomas are reported to be chemosensitive. Relatively little is known about the genetic aberrations in oligodendroglial tumors (OTs). In order to elucidate oligodendroglial oncogenesis and to find specific genetic aberrations that may have prognostic and therapeutic implications, we performed comparative genomic hybridization (CGH) to detect chromosomal copy number changes in 17 low-grade OTs (LG-OTs) and 12 high-grade OTs (HG-OTs) lacking a prominent astrocytic component. Loss of chromosome 1p (79%) and 19q (76%) were most frequently detected by CGH, all LG-OTs and 50% of the HG-OTs contained -1p (including 1p36-32), -19q (including 19q13.3), or both, and the rest of the HG-OTs showed +7, -10, or both. Since losses of 1p36-32 and 19q13.3 were mutually exclusive with +7 or -10, the HG-OTs could be divided in -1p/-19q and +7/-10 tumors. While the -1p/-19q tumors can be considered as pure anaplastic oligodendrogliomas, the +7/-10 tumors may rather be glioblastomas with prominent oligodendroglial differentiation. We conclude that CGH is a powerful tool to assist in the identification of 2 major subgroups of HG-OTs with prognostic and possibly therapeutic relevance.     

Desmoplastic infantile astrocytoma and ganglioglioma: a search for genomic characteristics

In the present study the clinical data, histology, proliferation rate, DNA ploidy status and the results of TP53 mutation analysis and comparative genomic hybridization (CGH) of three typical cases of desmoplastic infantile astrocytoma and ganglioglioma are presented. Postoperative disease-free intervals of 11, 8 and 3 years were recorded and in none of the cases were radiological signs of tumor recurrence. No TP53 mutations (exons 5-8) were found. CGH analysis revealed loss of 8p22-pter in one case, while in another case gain of 13q21 was detected. In the case with the follow-up of 11 years an aneuploid DNA-flow cytogram along with slightly increased MIB-1 labeling index (LI) was found. The results demonstrate little genetic instability in these low-grade lesions. DNA-aneuploidy seems not to be indicative of tumor progression. It is concluded that the genetic aberrations found in desmoplastic infantile ganglioglioma differ from those encountered in common astrocytomas.     

Comparative genomic hybridization analysis of genomic alterations in benign,atypical and anaplastic meningiomas

BACKGROUND: Meningiomas are common tumors of the central nervous system. Although most are benign tumors, approximately 10% show a histologic progression to a higher malignancy grade similar to atypical (GII) and anaplastic (GIII) meningiomas. Monosomy 22q12 is the most frequent genetic alteration detected in these tumors, but failure of detection of 22q mutations in about 40% of tumors which are indistinguishable from meningiomas with 22q deletions with respect to clinical and histopathologic features, makes it apparent that an alternative mechanism is responsible for the initiation of meningioma. Moreover, little is known about genetic alterations during malignant progression of meningioma. PURPOSE: In order to determine the genetic pathways underlying the development of meningioma, 15 benign (WHO grade I), 7 atypical (WHO grade II) and 3 anaplastic (WHO grade III), sporadic meningiomas were screened by Comparative Genomic Hybridization (CGH). RESULTS: Statistical analysis revealed a significant correlation between the number of chromosomal imbalances and the tumor grade; the numbers of total alterations detected per tumor were 2.20 (2.24 for GI, 10.00 (1.17 for GII and 14.66 (1.15 for GIII. The most frequent abnormality seen in benign tumors was loss on 22q (47%). The second alteration was 1p deletion (33%) and this abnormality was also the common aberration in three tumors without CGH detected 22q deletion. In GII, aberrations most commonly identified were losses on 1p (6/7 cases), 22q (5/7 cases), 10q (4/7 cases), 14q and 18q (3/7 cases) as well as gains on 15q and 17q (3/7 cases). In GIII, genomic loss on 1p was the most commonly observed abnormality (3/3). Losses on 9p, 10q, 14q, 15q, 18q and 22q as well as gains on 12q, 15q and 18p were the other genomic alterations detected by CGH. Combined 1p/14q deletions were encountered in 2/15 benign, 3/7 atypical and 2/3 anaplastic meningiomas. By CGH, DNA sequences on 17q21-qter were seen to be amplified in 1/7 GII and 2/3 GIII, whereas highly amplified DNA sequences on 12q13-qter, 20q and 22q11-q12 were seen in one GII, two GII/one GIII, and one GIII, respectively. CONCLUSION: It was concluded that chromosomal deletion from 1p could play a major role in the initiation and progression of meningiomas and that 1p/14q deletions could be a primary focus of further detailed assessment of tumour genesis.     

Comparative genomic hybridization in pineal germ cell tumors

Fifteen primary pineal germ cell tumors (8 germinomas, 4 mixed teratomas-germinomas, 2 immature teratomas, and 1 yolk sac tumor) and 2 recurrences of the yolk sac tumor were studied by comparative genomic hybridization (CGH). An average of 1.8 chromosomal changes per germinoma (0.5 gains vs 1.3 losses), 5.5 per mixed teratoma-germinoma (3.0 gains vs 2.5 losses), 3.5 per immature teratoma (2.0 gains vs 1.5 losses), and 2.0 in the yolk sac tumor (2 gains vs 0 losses) were found; the first recurrence showed 7 (4 gains vs 3 losses), the second 13 imbalances (8 gains vs 5 losses). The most frequent imbalances were gains on 12p (40%), 8q (27%), and 1q (20%) as well as losses on 13q (47%), 18q (33%), 9q and 11q (20% each). Among germinomas, the most common chromosomal changes were -13q and -18q (38% each), in mixed teratomas-germinomas +8q (100%), +12p (75%), -13q (75%) and -9q (50%). Seven high-level gains were identified: 5 in mixed teratomas-germinomas (+8q: 3 cases, + 12p: 2 cases), 1 each in a germinoma (+2p) and an immature teratoma (+12p). Minimal common regions of over- and underrepresentation were found on +8q11.22-21.1, +12p11.1-12.1, -9q32-qter, -11q23.2-qter, -13q32-qter and -18q22-qter. Our findings suggest, that imbalances in cerebral germ cell tumors affect the same chromosomes as among their extracerebral counterparts, albeit in a considerably lower frequency among cerebral germinomas where +12p does not seem to play a major role.     

Chromosomal imbalances detected by comparative genomic hybridisation in atypical teratoid/rhabdoid tumours

Introduction Atypical teratoid/rhabdoid tumours (AT/RT) are highly malignant embryonal tumours of the brain composed of rhabdoid cells. Inactivating mutations of the hSNF5/INI-1 gene located in the chromosomal region 22q11.2 are regarded as a crucial step in their molecular pathogenesis. Apart from monosomy or deletions of chromosome 22 not much data exists on additional chromosomal aberrations.Methods We investigated seven primary AT/RT by comparative genomic hybridisation (CGH) and found DNA copy number changes in each case.Results These consisted of loss of 22q in 7 out of 7 (100%) and loss of 19 in 3 out of 7 (43%) patients. In 4/7 AT/RT (57%), loss of chromosome 22q was the sole aberration whereas one patient showed additional losses of 16p, 17p and 20q.Conclusions Our CGH data suggest that apart from monosomy 22 additional genetic pathways may seem feasible for a subset of AT/RT that is yet to be defined. Furthermore, this study also emphasises the potential practical value of loss of chromosome 22 as a diagnostic marker for AT/RT.     

Characterisation of molecular alterations in microdissected archival gliomas

Classification of gliomas according to their molecular characteristics may be important in future histopathological diagnosis. However, gliomas frequently display heterogeneity at the histological, biological and molecular level. In this study of archival diagnostic gliomas, precision microdissection was used to enrich samples in the most malignant cells or to investigate intratumoural histological heterogeneity. Analysis of tumour samples microdissected from the most aggressive regions, representative of the histopathological diagnosis, revealed PTEN mutations in 4/14 anaplastic astrocytomas, 4/13 glioblastomas and 1 gliosarcoma, but not in 19 low-grade gliomas. Using a novel PCR procedure and direct sequence analysis of the entire coding sequence, TP53 mutations were detected in 1/3 pilocytic astrocytomas, 3/13 astrocytomas, 4/14 anaplastic astrocytomas, 5/13 glioblastomas and 1 gliosarcoma. All but one of the tumours with TP53 mutation showed p53 immunopositivity, but 5 low-grade and 10 high-grade gliomas had p53 protein nuclear accumulation in the absence of detectable mutation. p53 status was unrelated to p21 expression. Neither PTEN nor TP53 mutations influenced the proliferative index or microvessel density of high-grade astrocytomas. Unusual findings include: TP53 mutation in a juvenile pilocytic astrocytoma; TP53 and PTEN mutations in a de novo glioblastoma, a gliosarcoma with identical mutations in gliomatous and sarcomatous components, and an infratentorial anaplastic astrocytoma with an earlier supratentorial grade II astrocytoma bearing the same TP53 mutation but not the PTEN mutation or loss of heterozygosity (LOH) of 10q23. Similarly, the transition to high-grade histology was associated with acquisition of PTEN mutations and 10q23.3 LOH in two de novo high-grade tumours with regions of low-grade histology.     

Genetic alterations commonly found in diffusely infiltrating cerebral gliomas are rare or absent in pleomorphic xanthoastrocytomas

Pleomorphic xanthoastrocytoma (PXA) is a rare, usually well-circumscribed and superficially located neoplasm that preferentially arises in the cerebral cortex of children and young adults. The molecular aberrations that are associated with these tumors have not been studied systematically so far. We here report on a molecular genetic analysis of 62 PXAs (46 PXAs of World Health Organization [WHO] grade II and 16 PXAs with anaplastic features) for alterations of 5 candidate genes known to be frequently aberrant in diffusely infiltrating astrocytic gliomas, i.e. TP53, CDKN2A (p16(INK4a)), CDK4, MDM2, and EGFR. Only 3 PXAs (5%) carried a TP53 mutation. None of the 62 PXAs had lost both copies of the CDKN2A gene. The CDK4, MDM2, or EGFR genes were not amplified in any of the tumors. Fourteen PXAs were additionally analyzed for loss of heterozygosity (LOH) at microsatellite markers located on the chromosomes/chromosomal arms 1, gp, 9p, 10, 17, 19q, and 22q. Two PXAs (14%) had LOH at all informative markers on 9p, while 1 PXA demonstrated an interstitial area of allelic imbalance between D22S533 and D22S417 at 22q11.2-q13.3. Further analysis of 10 PXAs for inactivation of the CDKN2A. p14(ARF), and CDKN2B (p15(INK4b)) genes on 9p21 did not reveal any homozygous deletion, mutation, promoter hypermethylation, or complete loss of mRNA expression. Taken together, our results indicate that the chromosomal and genetic aberrations in PXAs are different from those typically associated with the diffusely infiltrating astrocytic and oligodendroglial gliomas. These genetic differences likely contribute to the more favorable behavior of PXAs and may be helpful for the molecular differential diagnosis of cerebral gliomas.     

Molecular analysis of microdissected de novo glioblastomas and paired astrocytic tumors

Glioblastoma multiforme (GBM) often displays morphological heterogeneity in that low-grade (LG) area with well-differentiated cells are commonly found adjacent to high-grade (HG) area with poorly-differentiated cells. This heterogeneity may cause difficulty in obtaining representative tumor samples. Nevertheless, the genetic composition of these cells has only been occasionally examined. In the present study, we examined 29 de novo glioblastomas in which distinct LG and HG areas of sufficient volumes could be identified. These areas were microdissected from paraffin-embedded tissues and analyzed for genetic alterations: p53 mutations and immunohistochemistry; allelic losses at 17p13.1, 9p21, and 10q23-25; and amplification of the epidermal growth factor receptor (EGFR) gene and immunohistochemistry. We also examined 14 paired astrocytic tumors, in which a primary Grade II astrocytoma progressed over a period of time to a Grade III or Grade IV tumor. Our findings showed that the LG areas of the de novo glioblastomas exhibited numerous genetic aberrations, the proportion of which was increased in the HG areas. Genetic abnormalities seen in the LG areas were conserved in the HG areas suggesting that these morphologically different cellular subsets were derived from a common transformed clone. Also, the LG areas were genetically different from Grade II astrocytomas of the paired tumor group, in spite of their morphological similarity. In particular, the LG areas had more deletions on 10q23-25 (75% vs 20%, p = 0.04), but fewer p53 mutations (24% vs 71%, p = 0.003) and less p53 protein labeling (45% vs 79%, p = 0.04). These differences suggest that LG and HG areas in de novo glioblastoma are genetically closer to each other compared with paired low- and high-grade tumors that have progressed over time. Moreover, only a small proportion (17%) of our de novo glioblastomas exhibited EGFR amplification while a high proportion (62%) showed either p53 mutations or allelic loss of 17p13.1. We speculate that some de novo GBMs with copious LG areas may constitute a separate group with rapid progression from Grade II astrocytomas.     

Investigating the genetic basis of fever‐associated syndromic epilepsies using copy number variation analysis

Fever‐associated syndromic epilepsies ranging from febrile seizures plus (FS+) to Dravet syndrome have a significant genetic component. However, apart from SCN1A mutations in >80% of patients with Dravet syndrome, the genetic underpinnings of these epilepsies remain largely unknown. Therefore, we performed a genome‐wide screening for copy number variations (CNVs) in 36 patients with SCN1A‐negative fever‐associated syndromic epilepsies. Phenotypes included Dravet syndrome (n = 23; 64%), genetic epilepsy with febrile seizures plus (GEFS+) and febrile seizures plus (FS+) (n = 11; 31%) and unclassified fever‐associated epilepsies (n = 2; 6%). Array comparative genomic hybridization (CGH) was performed using Agilent 4 × 180K arrays. We identified 13 rare CNVs in 8 (22%) of 36 individuals. These included known pathogenic CNVs in 4 (11%) of 36 patients: a 1q21.1 duplication in a proband with Dravet syndrome, a 14q23.3 deletion in a proband with FS+, and two deletions at 16p11.2 and 1q44 in two individuals with fever‐associated epilepsy with concomitant autism and/or intellectual disability. In addition, a 3q13.11 duplication in a patient with FS+ and two de novo duplications at 7p14.2 and 18q12.2 in a patient with atypical Dravet syndrome were classified as likely pathogenic. Six CNVs were of unknown significance. The identified genomic aberrations overlap with known neurodevelopmental disorders, suggesting that fever‐associated epilepsy syndromes may be a recurrent clinical presentation of known microdeletion syndromes.     

Intratumoral patterns of clonal evolution in gliomas

Few studies have explored the patterns of clonal evolution in gliomas. Here, we investigate the cytogenetic patterns of intratumoral clonal evolution of gliomas and their impact on tumor histopathology and patient survival. Cytogenetic analysis of 90 gliomas was performed in individual tumor cells (>200 cells/tumor) using multicolor (N = 16 probes) interphase—FISH. Overall, chromosome gains were more frequent than chromosome losses. Gains of chromosome 7 and/or EGFR amplification were detected in 91% of the cases, whereas del(9p21) (77%) and del(10q23) (78%) were the most frequent chromosome losses. Virtually, all cases (99%) showed ≥2 tumor cell clones, with higher numbers among high- versus low-grade gliomas (p = 0.001). Nine different cytogenetic patterns were found in the ancestral tumor clones. In most gliomas, ancestral clones showed abnormalities of chromosome 7, 9p, and/or 10q and cytogenetic evolution consisted of acquisition of additional abnormalities followed by tetraploidization. Conversely, early tetraploidization was associated with low-grade astrocytomas—2/3 pilocytic and 3/6 grade II diffuse astrocytomas—and combined loss of 1p36/19q13 with oligodendrogliomas, respectively; both aberrations were associated with a better patient outcome (p = 0.03). Overall, our results support the existence of different pathways of intratumoral evolution in gliomas     

Susceptibility loci for bipolar disorder: overlap with inherited vulnerability to schizophrenia.

Genetic epidemiological studies reveal that relatives of bipolar probands are at increased risk for recurrent unipolar, bipolar, and schizoaffective disorders, whereas relatives of probands with schizophrenia are at increased risk for schizophrenia, schizoaffective, and recurrent unipolar disorders. The overlap in familial risk may reflect shared genetic susceptibility. Recent genetic linkage studies have defined confirmed bipolar susceptibility loci for multiple regions of the human genome, including 4p16, 12q24, 18p11.2, 18q22, 21q21, 22q11-13, and Xq26. Studies of schizophrenia kindreds have yielded robust evidence for susceptibility at 18p11.2 and 22q11-13, both of which are implicated in susceptibility to bipolar disorder. Similarly, confirmed schizophrenia vulnerability loci have been mapped, too, for 6p24, 8p, and 13q32. Strong statistical evidence for a 13q32 bipolar susceptibility locus has been reported. Thus, both family and molecular studies of these disorders suggest shared genetic susceptibility. These two groups of disorders may not be as distinct as current nosology suggests.     

A Girl with Pervasive Developmental Disorder and Complex Chromosome Rearrangement Involving 8p and 10p

We report a 4-year-old girl with a de novo, apparently balanced complex chromosome rearrangement. She initially presented for assessment of velopharyngeal insufficiency due to hypernasal speech. She has distinctive facial features (long face, broad nasal bridge, and protuberant ears with simplified helices), bifid uvula, strabismus, and joint laxity. She is developmentally delayed, with language and cognitive skills approximately 2 SD below the mean expected for her age, and meets ADI, ADOS, and DSM-IV criteria for perva- sive developmental disorder. She has poor eye contact, atypical communication and social interaction, repetitive behaviours and significant difficulties with processing sensory input. Her karyotype is characterized by the presence of two derivative chromosomes; 46,XX, der(8)(10pter->10p12.32::8p12−>8qter), der(10)(8pter->8p21.3::10p12.32−>10p11.23::8 p21.3−> 8p12::10p11.23−>10qter). The der(8) is a result of translocation of the segment 10p12.32−pter onto 8p12. The der(10) has two 8p segments collectively from 8p12-pter in that the segment 8p21.3-pter is translocated onto 10p12.32 and the segment 8p12-p21.3 is inserted at 10p11.23. FISH analysis showed no microdeletion of the major locus at 22q11.2 nor for the minor locus at 10p13p14. This case suggests that aberrations at 8p12, 8p21.3, 10p11.23 and/or 10p12.32 may result in pervasive developmental disorder, associated with mild cognitive delay and specific facial anomalies.     

少突胶质细胞起源肿瘤染色体DNA失衡的比较基因组杂交研究

目的 探讨少突胶质细胞起源肿瘤基因组DNA失衡及其与病理分级的关系.方法 用比较基因组杂交技术检测了33例少突胶质细胞起源肿瘤石蜡包埋组织,分析其全基因组DNA失衡状况.结果 少突胶质细胞瘤(ODG)及间变性少突胶质细胞瘤(AODG)的基因组DNA失衡检出率分别为100%(16/16)和88%(15/17),共发现24个有DNA获得和24个有DNA丢失的染色体区带.其中,-19q、-1p/-19q联合性缺失检出率在ODG组明显高于AODG组(P<0.05),+7p检出率在AODG组明显高于ODG组(P<0.05).在22对常染色体及X染色体中,+1q、+7P、+8P、+8q、+9q、+18p、+18q、+20p及-1p、-19q、-Xq出现频率较高.+2q、+4p、+4q、+6p、+10p、+15q、+20q、+22q仅见ODG组,+11q、+12p、+Xp仅见于AODG组.而-3p、-5q、-8p、-12p、-12q、-15q、-19p、-20q、-XP仅见ODG组,-2q、-4p、-4q、-5p、-6q、-7p、-11q、-14q仅见于AODG组.结论 ODG和AODG均有各自特征性的染色体基因组DNA失衡谱;-1p/-19q是评价国人该类肿瘤生物学行为的重要参考指标,对治疗敏感性及患者预后判断有重要的指导意义;+7p和-19q对评估国人该类肿瘤的生物学行为和患者预后有一定参考价值.

Abstract：

Objective To investigate the relationship between genomic DNA imbalance in oligodendroglial tumors and its different classification.Method 16 oligodendrogliomas and 17 anaplastic oligodendrogliomas were investigated by comparative genomic hybridization on Paraffin-Embedded tissue samples, and the chromosomal genomic DNA imbalances were analyzed.Results Chromosome DNA imbalance rates in oligodendrogliomas and anaplastic oligodendrogliomas are 100% and 88% respectively,and chromosomal regions of 24 gains and 24 losses were found in these tumors.19q loss and 1p/19q loss are frequent in oligodendroglioma.The gain of 7p happened predominantly in anaplastic oligodendroglioma, and their differences were significant(P < 0.05 ).+ 1q, + 7p, + 8p, + 8q, + 9q, + 18p, + 18q, + 20p and-1p,-19q,-Xq are frequently occurred in oligodendroglial tumors.+2q, +4p, +4q, +6p, + 10p,+ 15q, + 20q and + 22q are only identified in oligodendroglioma, + 11q, + 12p and + Xp are only identified in anaplastic oligodendroglioma.-3p,-5q,-8p,-12p,-12q,-15q,-19p,-20q and-Xp are only identified in oligodendroglioma, and-2q,-4p,-4q,-5p,-6q,-7p,-11q and-14q are only identified in anaplastic oligodendroglioma.Conclusions The characteristic imbalance spectrum of oligodendroglial tumors is the molecular genetic base to determine their histological phenotype and grade.-1p/-19q are also the important molecular genetic markers to estimate biological behavior,chemotherapy sensitivity of these tumors and patients' prognosis.+7p and-19q may be useful to evaluate the biological behavior of these tumors and patients' prognosis.     

Evidence of focal genetic microheterogeneity in glioblastoma multiforme by area-specific CGH on microdissected tumor cells.

The term "multiforme" in glioblastoma multiforme (GBM) indicates the highly variable histomorphology that cannot be addressed by studies on homogenized tissue probes. In order to relate genetic findings with histomorphologically distinct areas we used microdissection to procure defined cell populations from microscopic tissue sections under direct visualization. Formalin-fixed and paraffin-embedded tissue sections of 10 GBM were evaluated for intratumoral genetic heterogeneity by microdissection of multiple areas of 20-50 tumor cells and DOP-PCR of DNA isolated from the dissected cell groups, followed by comparative genomic hybridization (CGH). Microdissected cells from histomorphologically normal extratumoral blood vessels from the same slides served as controls. The individual tumors showed variable combinations of primary chromosomal gains and losses common to all studied areas of a given case along with secondary, area-specific additional aberrations. CGH displayed a wider variety of chromosomal aberrations than metaphase cytogenetics of cell cultures from the same tumors. The most frequent aberrations observed were previously unperceived gains on chromosomes 4q (8/10) and 5q (5/10). Other nonrandom aberrations were gains on 12q (6/10), 13q (6/10), and 7 (5/10), and losses of 22 (5/10). Amplifications on 7p were intratumorally heterogeneous and only found in single areas of 2 tumors. In contrast to normal extratumoral vessels, vascular proliferates in most cases demonstrated chromosomal aberrations (CGH) which were partially different from the aberrations observed in the tumor itself. The described method gives evidence of considerable intratumoral genetic heterogeneity in GBM and provides a sensitive tool for the detection of quantitative chromosomal changes that are present only regionally within a given tumor.     

Immunohistochemical markers for intracranial ependymoma recurrence. An analysis of 88 cases

Intracranial ependymomas are the third most common primary brain tumor in children. Although clinical and histological criteria for ependymoma prognosis are recognized, studies have reported contradictory results. Prognostic significance based on immunohistochemistry of ependymomas has been reported in a few studies. Eighty-eight patients with intracranial ependymomas were examined retrospectively for immunoexpression of various tumor-associated antigens and apoptosis. The results demonstrated significant preponderance of expression of the tenascin, vascular endothelial growth factor protein (VEGF), epidermal growth factor (EGFR), and p53 protein in high-grade tumors. Also high-grade ependymomas revealed more prominent labeling indices (LI) for proliferative marker Ki-S1 and lower LI for cyclin-dependent kinase inhibitor p27/Kip1. For low-grade ependymomas the progression free survival time (PFS) was found to be significantly shorter for Ki-S1 LI>/=5%, and for tenascin, VEGF, and EGFR positivity. For high-grade ependymomas PFS was found to be significantly reduced for age <16 years, subtotal tumor removal, p27 LI <20%, p53 positivity, and for apoptotic index (AI) <1%. The classification regression tree analysis exhibited four groups of ependymomas; (1) low-grade tenascin negative (32 cases, recurrence rate=0), (2) high-grade with AI >/=1% (21 cases, recurrence rate=57%), (3) low-grade tenascin-positive (10 cases, recurrence rate=89%), and (4) high-grade with AI <1% (25 cases, recurrence rate=100%). So, the immunohistochemical variables were found to be strongest predictors of ependymoma recurrence and they seem to be useful for assessing individual tumor prognosis in routinely processed biopsy specimen.     

Molecular abnormalities in pediatric embryonal brain tumors--analysis of loss of heterozygosity on chromosomes 1, 5, 9, 10, 11, 16, 17 and 22

Embryonal tumors, the most common group of malignant brain tumors in childhood, are heterogeneous and have been associated with a large number of genetic abnormalities. The aim of this study was to comprehensively analyze loss of heterozygosity (LOH) on regions harboring suppressor genes (PTCH2, PTCH1, APC, PTEN, DMBT1, SUFU, AXIN1, hSNF5/INI1) and to study chromosomal regions in which deletions have been described most frequently (1p, 1q, 11p, 16p, 17p). Twenty-nine children (17 male and 12 female), aged from 1 year 13 years were included in this study. There were 24 medulloblastomas (MB) and 5 supratentorial primitive neuroectodermal tumors (sPNET). Tissue samples from 29 primary and 11 recurrent tumors were analyzed according to the LOH standard procedures, which were extended to include fluorescence in situ hybridization for detection of isochromosome 17q (i(17q)) and direct sequencing ofTP53 exon 4. LOH on 17p was found in 15 out of 29 tumors. FISH analysis identified the presence of i(17q) in 16 tumors. Comparison of LOH analysis and the FISH data indicated that alterations of 17p were related to be the introduction of an i(17q) formation. LOH on 10q and 9q was observed in 4 and 2 cases, respectively, and was associated with alterations of chromosome 17. These results indicated a connection between alterations of PTCH/SHH genes and abnormalities of chromosome 17. A deleted region on 22q, covering the hSNF5/INI1 locus, was observed in 3 tumors. Progression of the molecular changes occurred in 1 case of recurrent medulloblastoma. LOH on 10q and 17p was found in both primary and recurrent tumor, while losses on 11p, 16p, and 16q occurred only in the recurrent tumor. No evidence of alteration in TP53 exon 4 was identified.