IDH3A and brain neoplasm: In contrast to this broad range of findings, 1H-MRS detection of 2-hydroxyglutarate for brain tumor characterization, a rare category of 1H-MRS clinical applications for which insurance reimbursement is sometimes considered (14), has previously demonstrated in at least one analysis all-or-nothing association with the presence of isocitrate dehydrogenase mutation status in gliomas (295), supporting, according to a 2018 meta-analysis of 14 studies, a pooled sensitivity of 95% (296).