Diffuse midline gliomas with subclonal H3F3A K27M mutation and mosaic H3.3 K27M mutant protein expression
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Diffuse midline gliomas are aggressive tumors centered in midline structures of the brain that most commonly occur in children and young adults . They are genetically defined by the presence of K27M mutation in either the H3F3A or HIST1H3B genes, which encode the histone H3 variants H3.3 and H3.1, respectively . Given their poor prognosis, the 2016 WHO Classification includes “Diffuse midline glioma, H3 K27M-mutant” as a WHO grade IV entity, even in cases where only lower-grade histologic features are present . In all cases reported to date, H3 K27M mutation has been a clonal alteration in all regions of tumors assessed by sequencing, and immunostaining with antibodies against H3 K27M mutant protein has revealed uniform expression in all tumor cells [2, 5, 6]. Thus, it has been hypothesized that H3 K27M mutation is the earliest or initiating genetic alteration during gliomagenesis in these tumors. Here we describe two cases of diffuse midline glioma with subclonal H3F3AK27M...
DAS is supported by NIH Director’s Early Independence Award (DP5 OD021403) and the UCSF Physician-Scientist Scholar Program.
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Conflict of interest
The authors declare that they have no competing interests related to this case report.
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