PCR-Based Simple Subgrouping Is Validated for Classification of Gliomas and Defines Negative Prognostic Copy Number Aberrations in <i>IDH</i> Mutant Gliomas

<div><p>Genetic subgrouping of gliomas has been emphasized recently, particularly after the finding of <i>isocitrate dehydrogenase 1</i> (<i>IDH1</i>) mutations. In a previous study, we investigated whole-chromosome copy number aberrations (CNAs) of gliomas and have described genetic subgrouping based on CNAs and <i>IDH1</i> mutations. Subsequently, we classified gliomas using simple polymerase chain reaction (PCR)-based methods to improve the availability of genetic subgrouping. We selected <i>IDH1/2</i> and <i>TP53</i> as markers and analyzed 237 adult supratentorial gliomas using Sanger sequencing. Using these markers, we classified gliomas into three subgroups that were strongly associated with patient prognoses. These included <i>IDH</i> mutant gliomas without <i>TP53</i> mutations, <i>IDH</i> mutant gliomas with <i>TP53</i> mutations, and <i>IDH</i> wild-type gliomas. <i>IDH</i> mutant gliomas without <i>TP53</i> mutations, which mostly corresponded to gliomas carrying 1p19q co-deletions, showed lower recurrence rates than the other 2 groups. In the other high-recurrence groups, the median progression-free survival (PFS) and overall survival (OS) of patients with <i>IDH</i> mutant gliomas with <i>TP53</i> mutations were significantly longer than those of patients with <i>IDH</i> wild-type gliomas. Notably, most <i>IDH</i> mutant gliomas with <i>TP53</i> mutations had at least one of the CNAs +7q, +8q, −9p, and −11p. Moreover, <i>IDH</i> mutant gliomas with at least one of these CNAs had a significantly worse prognosis than did other <i>IDH</i> mutant gliomas. PCR-based mutation analyses of <i>IDH</i> and <i>TP53</i> were sufficient for simple genetic diagnosis of glioma that were strongly associated with prognosis of patients and enabled us to detect negative CNAs in <i>IDH</i> mutant gliomas.</p>