Idh1 mutation in balinese glioma patients and its relationship with clinicopathological parameters

Abstract

Purpose: Isocitrate dehydrogenase 1 (IDH1) mutation plays an essential role in the carcinogenesis of gliomas. The most recent WHO classification of central nervous system tumors has added molecular genetic and histological features of the tumor, including IDH mutation in glial tumors. This study aimed to determine the prevalence of IDH1 mutations in Balinese glioma patients and its association with clinicopathological features. Patients and methods: This was a cross-sectional study involving 30 glioma patients at Sanglah General Hospital from January 2018 until June 2019. DNA extractions were carried out from the FFPE of tumor tissue, followed by amplification of codon 132 in exon 4 of the IDH1 gene by allele-specific PCR. The relationship between IDH1 mutation status and clinicopathological features was tested with X2 with 0.05 significance. Results: The age range of patients is 14-81 years, with an average age of 43.4 years (SD±17.9 years). Most patients with astrocytic tumors (25/30; 83.3%), others were oligodendroglial tumor (2/30; 6.7%) and oligoastrocytic tumor (3/30; 10%). Most patients were found with grade IV glioblastoma (18/30; 60%). Genotyping analysis showed IDH1 mutations in the majority of glioma patients (90%). Most cases (92.6%) of mutant IDH1 showed heterozygous mutations (GA genotype), while the rest showed homozygous mutations (AA genotype). There was no significant relationship between IDH1 status and age (p=0.09), sex (p=0.63) and histologic type (0.14), but there was significant relationship between IDH1 mutation status and tumor grade (p=0.01). All of the IDH1 mutations were found in diffuse glioma (grade II and III gliomas and grade IV glioblastoma). Conclusion: Most of the diffuse glioma (grade II-IV glioma) patients in Bali had IDH1 mutation, and IDH1 mutation status has significant relationship with tumor grade. Further research about genetic abnormalities to improve therapeutic efficacy against IDH-mutated gliomas is needed.