Thus, despite the association between the sporadic forms of high-grade glioma and abnormalities of p16(INK4A), p15(INK4B), or CDK4, we found no evidence that germ-line mutations in the coding region of these three genes predispose to inherited glial tumors.
The occurrence of p16/CDKN2 germline mutations in 12 Icelandic melanoma kindreds (kindreds with two or more cases of melanoma or melanoma, pancreas and/or glioma cases) was examined.
We identified five risk loci for glioma at 5p15.33 (rs2736100, TERT; P = 1.50 x 10(-17)), 8q24.21 (rs4295627, CCDC26; P = 2.34 x 10(-18)), 9p21.3 (rs4977756, CDKN2A-CDKN2B; P = 7.24 x 10(-15)), 20q13.33 (rs6010620, RTEL1; P = 2.52 x 10(-12)) and 11q23.3 (rs498872, PHLDB1; P = 1.07 x 10(-8)).
The Investigating and defining if glial tumors with CDKN2A/B and MTAP homozygous loss may be vulnerable to new forms of therapy, namely those affecting the methionine salvage pathway, was proven to be of importance.
Six constitutional missense mutations of the p53 gene were identified (13.6%), but no mutations of the p16 and PTEN genes were found, suggesting that (1) germline p53 mutations contribute to a small portion of astrocytic tumors, (2) inherited mutations of the p16 and PTEN gene do not predispose to the development of gliomas, and (3) other genes are involved in glioma predisposition.
Three of the gene variants (rs4295627, a variant of CCDC26; rs4977756, a variant of CDKN2A and CDKN2B; and rs6010620, a variant of RTEL1) were statistically significantly associated with glioma risk in the present population.
The average percentage of methylation in the promoter region of p14ARF gene in brain samples from glioma patients is 39.4%, while 0 from autopsy donors.
These results might suggest that deletion of p16 genes promoted unrestrained growth in human glioma but has no relationship to the chemosensitivity to CDDP, ACNU and AZC.
Taken together with the facts that only one PXA preceded E-GBM among these lower-grade lesions, and that co-occurrence of BRAF V600E, TERT promoter mutations and CDKN2A/B homozygous deletions have been reported to be rare in conventional lower-grade diffuse gliomas, the diffuse glioma-like components may be distinct infiltrative components of E-GBM, reflecting intratumoral heterogeneity.
Genome-wide association data have identified common genetic variants at 5p15.33 (rs2736100, TERT), 8q24.21 (rs4295627, CCDC26), 9p21.3 (rs4977756, CDKN2A-CDKN2B), 11q23.3 (rs498872, PHLDB1), and 20q13.33 (rs6010620, RTEL1) as determinants of glioma risk.
Genome-wide association studies have recently identified single-nucleotide polymorphisms (SNP) in five loci at 5p15.33 (rs2736100, TERT), 8q24.21 (rs4295627, CCDC26), 9p21.3 (rs4977756, CDKN2A/CDKN2B), 20q13.33 (rs6010620, RTEL1), and 11q23.3 (rs498872, PHLDB1) to be associated with glioma risk.
Specific single nucleotides polymorphisms (SNPs) rs4977756 (CDKN2A/B), rs6010620 (RTEL1), rs498872 (PHLDB1), rs2736100 (TERT), and rs4295627 (CCDC26) have been associated with glioma susceptibility and are potential risk biomarkers.
Seven independent chromosomal loci have robustly been associated with glioma risk: 5p15.33 (rs2736100, TERT), 8q24.21 (rs4295627, CCDC26), 9p21.3 (rs4977756, CDKN2A-CDKN2B), 20q13.33 (rs6010620, RTEL1), and 11q23.3 (rs498872, PHLDB1), and two loci at 7p11.2 (rs11979158 and rs2252586, EGFR).
In this study, we analyzed the deletion status of all three exons of p16 and frequency of exon 2 somatic point mutations in glioma from the Indian population and its clinical implications.
Beside CDKN2A, other genes (e.g., CDKN2B, and ARF/p14(ARF), long considered distinct from CDKN2A) on this locus are often deleted or mutated in a large number of tumors including glioma, bladder cancer, and lung cancer.
Genome-wide association studies have identified single-nucleotide polymorphisms (SNPs) at 7 loci influencing glioma risk: rs2736100 (TERT), rs11979158 and rs2252586 (EGFR), rs4295627 (CCDC26), rs4977756 (CDKN2A/CDKN2B), rs498872 (PHLDB1), and rs6010620 (RTEL1).
The genetic variants associated with the risk of glioma in the EGFR gene have also been associated with specific somatic aberrations, including loss at the CDKN2A/B locus and allele specific loss of EGFR in the tumors.