NF1 and pilocytic astrocytoma: In about one third of cases of pilocytic astrocytomas with signs of anaplasia, germline or somatic NF1 mutations can be detected [27]; however, formal criteria for this subset of pilocytic astrocytomas or a typical methylation profile have not been defined and clinical information is sparse, but suggestive of substantially more aggressive behavior in most cases [23, 31, 32].