Background: IDH1 mutation shows diagnostic, prognostic, and predictive value in gliomas. Direct Sanger sequencing is considered the gold standard to detect IDH1 mutation. However, this technology is not available in most neuropathological centers in developing countries such as Indonesia. Immunohistochemistry (IHC) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) have also been used to detect IDH1 mutation. This study aimed to compare DNA sequencing, IHC, and PCR-RFLP in detecting IDH1 mutations in gliomas. Methods: Research subjects were recruited from Dr. Sardjito Hospital. Genomic DNA was extracted from fresh or formalin-fixed paraffin-embedded samples of tumor tissue. DNA sequencing, PCR-RFLP and IHC were performed to detect IDH1 mutation. Sensitivity, specificity, and accuracy of PCR-RFLP and IHC were calculated by comparing them to DNA sequencing as the gold standard. Results: Among 61 recruited patients, 13 (21.3%) of them carried a mutation in codon 132 of the IDH1 gene, as shown by DNA sequencing. PCR-RFLP and DNA sequencing have a concordance value of 100%. Meanwhile, the concordance value between IDH1 R132H IHC and DNA sequencing was 96.7%. The sensitivity, specificity, positive predictive values, negative predictive values, and accuracy for PCR-RFLP were all 100%. On the other hand, the sensitivity, specificity, and accuracy of IHC were 92.3%, 97.9%, and 96.7%, respectively. Conclusion: This study showed that both PCR-RFLP and IHC have high accuracy in detecting IDH1 mutation. We recommend a combination of PCR-RFLP and IHC to detect IDH1 mutation in resource-limited settings.

Background: Gliomas are the most frequent primary brain tumors. According to World Health Organization guidelines, gliomas are graded into four groups (Group I-IV). This histological grading will determine prognosis and treatment of the patient. Morphological criteria are not always accurate. Tumor proliferation index is a potent quantitative marker for tumor behavior and prognosis, also it's the basis of gliomagenesis. Ki-67 immunohistochemistry examination for determining proliferation index has been suggested as an ancillary marker in deciding the definitive grading of glioma. Objective: To analyze the correlation between Ki-67 labeling index and histopathological grading of glioma in Indonesian population. Methods: One hundred and six formalin fixed-paraffin embedded tissue of glioma patients were collected from 4 different hospitals. Expression of Ki-67 was detected using immunohistochemistry staining and the labeling index was counted. The association between Ki-67 labeling index and histopathological grading was analyzed. Results: Age range of patient were 1-73-years old, with male predominance (55.70%). Glioblastoma was the most common diagnosis accounting for 41.51% of all samples. Ki-67 labeling index cut point of 6.35% was obtained and significantly sensitive and specific for determining low-or high-grade glioma (p<0.001). Conclusion: A significant association between Ki-67 labeling index and histopathological grading in Indonesian glioma patients has been revealed. The result of this study may be used to improve diagnostic and grading accuracy of glioma cases in Indonesia, especially in small biopsy specimens.

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