Homozygous deletion of TNFRSF4, TP73, PPAP2B and DPYD at 1p and PDCD5 at 19q identified by multiplex ligation-dependent probe amplification (MLPA) analysis in pediatric anaplastic glioma with questionable oligodendroglial component.

BACKGROUND: Pediatric oligodendrogliomas are rare and appear to show a different molecular profile from adult tumors. Some gliomas display allelic losses at 1p/19q in pediatric patients, although less frequently than in adult patients, but this is rare in tumors with an oligodendroglial component. The molecular basis of this genomic abnormality is unknown in pediatric gliomas, but it represents a relatively common finding in pediatric oligodendroglioma-like neoplasms with leptomeningeal dissemination. RESULTS: Multiplex ligation-dependent probe amplification (MLPA) analysis using SALSA P088-B1 for the analysis of the 1p/19q allelic constitution in a pediatric anaplastic (oligodendro)-glioma showed homozygous co-deletion for markers: TNFRSF4 (located at 1p36.33), TP73 (1p36.32), PPAP2B (1pter-p22.1), DPYD (1p21.3), and PDCD5 (19q13.12), and hemizygous deletion of BAX (19q13.3-q13.4). No sequence changes for R132 and R172 of the IDH1/2 genes were identified. CONCLUSIONS: The molecular findings in this pediatric anaplastic glioma do not allow for a clearly definitive pathological diagnosis. However, the findings provide data on a number of 1p/19q genomic regions that, because of homozygotic deletion, might be the location of genes that are important for the development and clinical evolution of some malignant gliomas in children.

NF2 genetic alterations in sporadic vestibular schwannomas: clinical implications.

HYPOTHESIS: NF2 gene alterations may have a clinical impact in non-NF2 vestibular schwannomas (VSs). BACKGROUND: It has been suggested that NF2 mutations might correlate with clinical expression of VS in NF2 patients. The aim of this study was to analyze the impact of genetic alterations in the NF2 gene on epidemiologic, clinical, and radiologic features of patients with sporadic VS. The association between cigarette consumption and the molecular genetic findings was also studied. METHODS: The study group consisted of 51 patients who underwent surgery for removal of vestibular schwannoma in our institution between January 2006 and December 2010. Five highly polymorphic microsatellite DNA markers were used to observe the frequency of loss of heterozygosity (LOH) in chromosome 22. The NF2 gene mutations were detected using polymerase chain reaction amplification and denaturing high-performance liquid chromatography analysis (PCR/dHPLC), and direct sequencing of NF2. Multiplex ligation-dependent probe amplification (MLPA) of the NF2 gene was also performed. RESULTS: An NF2 mutation was identified in 49%, 22q LOH in 57%, and MLPA alterations in 13.7% of the cases. One mutational hit was present in 27%, and 2 hits were present in 45% of the tumors. No association was found between the type of NF2 mutation and relevant clinical parameters. The presence of NF2 mutations detected by PCR/dHPLC was associated with no complaint of hearing loss at the time of diagnosis (p = 0.023), with subjective aural fullness (p = 0.022) and with an absence of tumor involvement of the internal auditory canal (p = 0.029). Patients with NF2 mutations had lower mean corrected PTA thresholds compared with those with no NF2 mutation (p = 0.037). Inactivation of the NF2 gene by mutation, MLPA, or LOH was more frequent in smokers when compared with never smokers (p = 0.048). CONCLUSION: NF2 mutations may play a role in the pathophysiology of hearing loss as well as in the pattern of growth of VS. Cigarette smoking in patients with VS seems to play a role in both the risk of developing the tumor and also in its genetic profile. More studies are needed to corroborate these results and, more broadly, to establish links between molecular and clinical data.

Gene expression analysis of aberrant signaling pathways in meningiomas.

Examining aberrant pathway alterations is one method for understanding the abnormal signals that are involved in tumorigenesis and tumor progression. In the present study, expression arrays were performed on tumor-related genes in meningiomas. The GE Array Q Series HS-006 was used to determine the expression levels of 96 genes that corresponded to six primary biological regulatory pathways in a series of 42 meningiomas, including 32 grade I, four recurrent grade I and six grade II tumors, in addition to three normal tissue controls. Results showed that 25 genes that were primarily associated with apoptosis and angiogenesis functions were downregulated and 13 genes frequently involving DNA damage repair functions were upregulated. In addition to the inactivation of the neurofibromin gene, NF2, which is considered to be an early step in tumorigenesis, variations of other biological regulatory pathways may play a significant role in the development of meningioma.

Expression analysis of tumor-related genes involved in critical regulatory pathways in schwannomas.

PURPOSE: Gene expression array analysis is providing key data on the potential candidate genes and biological pathways involved in schwannoma origin and development. In this way we performed expression array studies on tumor-related genes in schwannomas. METHODS: The GE Array Q Series HS-006 (SuperArray, Bethesda, MD, USA) was used to determine the expression levels of 96 genes corresponding to 6 primary biological regulatory pathways in a series of 23 schwannomas. RESULTS: We identified 15 genes down-regulated, primarily corresponding to signal transduction functions, and 26 genes up-regulated, most frequently involving cell adhesion functions. CONCLUSIONS: In addition to the NF2 inactivation (considered as an early step), variations of other biological regulatory pathways might play a key role in schwannoma.