Mutation Profiling of Intracranial Myxopapillary Ependymoma by Next Generation DNA Sequencing.

Abstract

Objectives: Primary intracranial myxopapillary ependymomas (MPE) are very rare. In order to determine genomic changes in an intracranial MPE, we analyzed its mutation patterns by next generation DNA sequencing.

Methods: Tumor DNA was sequenced using an Ion PI v3 chip on Ion Proton instrument and the data were analyzed by Ion Reporter 5.6.

Results: In this tumor, NGS generated 6,298, 354 mapped reads using the Ion PI v3 Chip. The average reads per amplicon was 29,365, 100% of amplicons had at least 500 reads and the amplicons read end-to-end were 97.58%. In this tumor, NGS data analysis identified 12 variants, of which two were missense mutations, seven were synonymous mutations and three were intronic variants. Missense mutation in c.395G>A; in exon 4 of the IDH1 gene, and a missense mutation in c.215C>G; in exon 4 of the TP53 gene were found in this tumor were previously reported. The known synonymous mutations were found in this tumor were, in exon 14 of FGFR3 in c.1953G>A; in exon 12 of PDGFRA in c.1701A>G; in exon 18 of PDGFRA c.2472C>T; in exon 20 of EGFR in c.2361G>A; in exon 13 of RET in c.2307G>T; in exon 16 of APC in c.4479G>A; and in exon 2 of MET in c.534C>T. Additionally, a known intronic variant was identified in KDR and a known acceptor site splice variant in FLT3 (rs2491231) and a SNP in the 3 ' -UTR of the CSF1R gene (rs2066934) were also identified. Except, the frequency of IDH1 variant, the frequencies of other variants were high, and the p-values were significant and Phred scores were high for all of these mutations.

Conclusions: The variants reported in this tumor have not been detected in myxopapillary grade I ependymoma tumor by NGS analysis previously and we therefore report these variants in this case for the first time.