10233-GMC-17 CLINICAL SIGNIFICANCE OF GENETIC ANALYSIS FOR GLIOMA CASES IN OUR INSTITUTE

Abstract

Abstract The WHO Classification the 5th edition describes that identification of alterations in IDH gene, histone H3 gene, CDKN2A gene, and other genes are quite important for the diagnosis and grading of diffuse gliomas. It is important to efficiently analyze important genetic abnormalities and utilize them in actual clinical practice. In our institute, we have recently performed genetic analysis which is important for the diagnosis of glioma in all patients. Here, we report the results of these analyses. From March 2019 to June 2023, we performed Sanger sequencing for analyses of IDH1/2, H3F3A, TERT promoter, BRAF, and FGFR1 mutation in 235 patients with suspected glioma who underwent biopsy or resection at our hospital and affiliated institutions. In 145 cases, we performed MLPA analyses for detection of 1p/19q codeletion, CDKN2A homozygous deletion (HD), EGFR amplification, and Chromosome 7p gain/10q loss. Sanger sequencing identified 81 TERT promoter mutations, 70 IDH mutations (including 3 IDH2 mutations), 8 BRAF V600E mutations, 4 H3 K27M mutations, 3 H3 G34R/V mutations, and 1 FGFR1 mutation The alterations most frequently identified in MLPA were CDKN2A HD in 26 cases and 1p/19q codeletion in 19 cases. Of the 214 cases in which the pathology diagnosis was neoplastic disease, 85 (39.8%) had no abnormalities in the above genetic analysis. In 32 of these cases, the pathological diagnosis was glioblastoma, IDH-wildtype, while in many other cases, the pathological diagnosis was low-grade glioma. Genetic analysis focusing on important genes for diagnosis according to WHO classification the 5th edition was useful for diagnosis in many cases, but careful consideration is needed for diagnosis in cases without these genetic alterations.