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We identified 16 HGG (11 glioblastomas, 3 anaplastic astrocytomas and 2 anaplastic gangliogliomas, 16/30, 53 %) and 1 diffuse astrocytoma harboring H3F3A K27M mutations ( Fig. 1a-e). The frequency of mutations among HGG affecting adults and children was similar (52 vs. 54 %). The mean age of adult patients with mutated tumors was lower (34 years) than that observed in patients with wild-type tumors (53 years) (Fig. 1f). All tumors affecting infants were H3F3A wild type. The distributions of mutated and wild-type HGG along the spinal cord appeared similar, but in cervical spine HGG were more frequently mutated (Fig. 1g). Neither H3F3A wild-type HGG nor DA showed immunoreactivity for mutant IDH1 R132H protein (not shown).Histones are nuclear proteins which regulate DNA replication and transcription by modifying the nucleosome structure [9]. H3.3 histone proteins, encoded by H3.3A (H3F3A) and H3.3B, are deposited on chromatin in a replication-independent manner and are enriched at actively transcribed genes and heterochromatic regions [9]. H3F3A mutations occur in a hotspot region (K27 and G34) undergoing posttranslational modifications. Similar to IDH1 mutated gliomas in adults, reduced H3.3K27 trimethylation and deregulated DNA methylation are considered to play a major role in pediatric gliomagenesis [2]. Recently, several groups have highlighted the high frequency of H3F3A K27M mutations in pediatric midline HGG as well as in DIPG [2, 3, 7, 8]. These mutations are not limited to pediatric patients, but can occur, although more rarely, in adults. H3F3A K27M mutations were frequently observed in thalamic HGG affecting young adults [1] and adult DIPG, but rare in supratentorial adult HGG [6]. Notably, the patient's age did not affect the pattern of methylation in H3F3A K27M mutant tumors [1].Diffuse high-grade gliomas (HGG) in the spinal cord are rare [5]. It is still undetermined whether they could share genetic alterations with their supratentorial counterparts: in particular, because the spinal cord has to be considered a midline structure, a high incidence of H3F3A K27M mutations could be hypothesized, as reported in diffuse pontine gliomas (DIPG) and in pediatric midline HGG [1-3, 6-8].In this study, we investigated the H3F3A K27M status of 30 primary spinal HGG affecting pediatric and adult patients.Formalin-fixed paraffin-embedded specimens of 36 primary spinal diffusely infiltrating gliomas, including 30 HGG (18 glioblastomas, WHO IV; 10 anaplastic astrocytomas, WHO III; 2 anaplastic gangliogliomas, WHO III) and 6 diffuse astrocytomas (WHO II) [5] were retrieved from the archives

Craniopharyngiomas are rare histologically benign but clinically challenging neoplasms. To obtain further information on the molecular genetics and biology of craniopharyngiomas, we analyzed a cohort of 121 adamantinomatous and 16 papillary craniopharyngiomas (ACP, PCP). We extracted DNA from formalin-fixed paraffin-embedded tissue and determined mutational status of CTNNB1, BRAF, and DDX3X by Sanger sequencing, next generation panel sequencing, and pyrosequencing. Sixteen craniopharyngiomas were further analyzed by molecular inversion profiling (MIP); 76.1% of the ACP were mutated in exon 3 of CTNNB1 encoding for β-catenin and there was a trend towards a worse event-free survival in cases mutated at Thr41. Next generation panel sequencing of 26 ACP did not detect any recurrent mutations other than CTNNB1 mutations. BRAF V600E mutations were found in 94% of the PCP, but not in ACP. GISTIC analysis of MIP data showed no significant larger chromosomal aberrations but a fraction of ACP showed recurrent focal gains of chromosomal material, other cases showed loss in the chromosomal region Xq28, and a third group and the PCP had stable genomes. In conclusion, the crucial pathogenetic event appears to be WNT activation in ACP, whereas it appears to be activation of the Ras/Raf/MEK/ERK pathway by BRAF V600E mutations in PCP.