Parsons et al. [42] showed the existence of a recurrent point mutation in the active region of IDH1, and this IDH1 mutation is tightly related with TP53 mutation with del(1p)/del(19q), which may indicate that an early event in IDH mutation is more common in secondary GBM (80%) compared to initial GBM (5%). The gene discussed is TP53; the disease is glioblastoma.