PIR and neoplasm: Five piRNAs (piR-hsa-1849, piR-hsa-5938, piR-hsa-9491, piR-hsa-12487, and piR-hsa-12488) selected based on NGS data as the five most significantly dysregulated piRNAs in GBMs were validated on an independent cohort of 77 GBM samples and 23 non-tumor controls.