Artikel
Comparison of fragment analysis and immunohistochemistry to conventional Sanger sequencing for the detection of R132H and non-R132H IDH1 mutations in gliomas
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Autoren
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Eva Heubeck
- Saarland University Medical Center, Institute of Pathology, Homburg, Germany; Klinikum Ingolstadt GmbH, Clinic of Neurology, Ingolstadt, Germany
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Nicole Ludwig
- Saarland University Medical Center, Department of Human Genetics, Homburg, Germany
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Elke Ebert
- Saarland University Medical Center, Institute of Pathology, Homburg, Germany
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Yoo-Yin Kim
- Saarland University Medical Center, Institute of Pathology, Homburg, Germany
| Veröffentlicht: | 25. August 2015 |
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Gliederung
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Introduction: Both, primary and secondary glioblastomas are CNS tumors with a very poor prognosis. Both entities differ in their IDH1 mutational status. This mutation represents an early event in tumorigenesis of glioma and is a prognostic parameter.
Objectives: To compare different detection methods of IDH1 mutations in terms of sensitivity, specificity, and feasibility in daily routine.
Materials & methods: For the detection of the IDH1 R132H mutation in FFPE samples of 43 glioblastomas and 42 WHO grade II and III gliomas, immunohistochemistry, Sanger sequencing, and fragment analysis were used. Clinical data including progression-free survival of the 43 glioblastoma patients was analyzed for each tested detection method with the IDH1 mutational status as independent variable.
Results: Immunohistochemistry detected IDH1 R132H mutation in 33 out of 85 samples. Only 24 were found to harbor IDH1 R132H mutation by fragment analysis and only 18 by Sanger sequencing. In two cases IDH1 R132G mutation could be detected by Sanger sequencing.
With immunohistochemistry as reference method a specificity of 100% and a sensitivity of 54.5% was calculated for Sanger sequencing and a specificity of 96.2% and a sensitivity of 66.7% for fragment analysis. Different to the other methods, immunohistochemistry enables the detection of single IDH1 R132H positive tumor cells in very diffuse areas or in small biopsy samples. The fragment analysis was superior to Sanger sequencing especially in small biopsies and diffuse neoplasia due to the lower demand of tumor DNA for the analysis.
Survival analysis revealed an increased overall survival for patients with IDH1 R132H mutation compared to those without. The prognosis was best predicted by the IDH1 R132H status detected by immunohistochemistry. The median survival was 51 ±32.4 months for IDH-1 R132H and 19 ±5 months for non IDH-1 R132H (log rank p=0.163). The prognostic value of direct sequencing (log rank p=0.294) was superior to fragment analysis (log rank p=0.312), though the effect was not statistically significant.
Conclusion: Our data show that IDH1 R132H immunohistochemistry is the most appropriate method to use in daily routine in terms of feasibility, detection rate as well as predictive value to estimate the patient’s prognosis.
