IDH1 and malignant glioma: Based on the molecular similarities that have been noted between primary pediatric malignant gliomas that arise in older children and secondary malignant gliomas that occur in adults, recently Pollack et al. examined the frequency of IDH mutations in a cohort of 43 HGG patients aged 3–21 years at the time of diagnosis [83]. IDH1 mutations were noted in 7 of 20 tumors (35%) from children ≥14 years, but in 0 of 23 (0%) younger children (P = 0.01), suggesting that a subset of such lesions may be comparable on a molecular basis to lesions that arise in young adults.