Project description:Genome wide DNA methylation profiling of human normal and epileptic brain tissue. The Illumina Infinium 850K Human DNA methylation Beadchip was used to obtain DNA methylation profiles across approximately 850.000 CpGs in formalin-fixed paraffin-embedded surgical brain samples. Samples included 316 cases diagnosed with malformations of cortical development (MCD), non-MCD epilepsy or no-epilepsy autopsy controls.
Project description:Cavitating ultrasonic aspirator devices are frequently used in pediatric neurosurgery for efficient microsurgical resection of brain tumours while minimizing tissue damage to surrounding healthy brain. Within this study molecular diagnostics using methylation-based classification of ultrasonic aspirated samples was performed and performance against routine microarray diagnostics was assessed.
Project description:Using a public reference data set of 82 unique entities, 382 nanopore-sequenced brain tumor samples were classified based on their methylation status through an ad hoc random forest algorithm. As a measure of confidence, score recalibration was performed and platform-specific thresholds were defined.
Project description:Background: DNA methylation-based classification of cancer provides a comprehensive molecular approach to diagnose tumours. In fact, DNA methylation profiling of human brain tumours already profoundly impacts clinical neuro-oncology. However, current implementations using hybridization microarrays are time-consuming and costly. We recently reported on shallow nanopore whole-genome sequencing for rapid and cost-effective generation of genome-wide 5-methylcytosine profiles as input to supervised classification. Here, we demonstrate that this approach allows to discriminate a wide spectrum of primary brain tumours.
Results: Using public reference data of 82 distinct tumour entities, we performed nanopore genome sequencing on N=382 tissue samples covering 46 brain tumour (sub)types. Using bootstrap sampling in a cohort of N = 56 cases, we find that a minimum set of 1,000 random CpG features is sufficient for high-confidence classification by ad hoc random forests. We implemented score recalibration as confidence measure for interpretation in a clinical context and empirically determined a platform-specific threshold in a randomly sampled discovery cohort (N = 185). Applying this cut-off to an independent validation series (N = 184) yielded 148 classifiable cases (sensitivity 80.4%) and demonstrated 100 % specificity. Cross-lab validation demonstrated robustness with concordant results across four laboratories in 10/11 (90.9%) cases. In a prospective benchmarking (N = 15), median time to results was 21.1 hours.
Conclusions: In conclusion, nanopore sequencing allows robust and rapid methylation-based classification across the full spectrum of brain tumours. Platform-specific confidence scores facilitate clinical implementation for which prospective evaluation is warranted and ongoing.