CHEK2 and glioblastoma: For all six PGVs (ATR, CHEK2 (3x), SDHA and MITF) without an established association with familial glioblastoma and for 10 out of 11 PGVs in recessive genes (BLM (4x), ERCC3, MUTYH (2x), FANCF, SBDS and WRN), no second (somatic) event (small variant or structural variant resulting in LOH) or matching mutational signature was detected in the tumor.