The presence of certain cancer-related genetic and epigenetic alterations in the tumor affects patient response to specific cancer therapies. The accurate screening of these predictive biomarkers in molecular diagnostics is important since it enables the tailoring of optimal treatment based on molecular characteristics of the tumor. We searched the electronic database PubMed for preclinical as well as clinical controlled trials reporting on various multiple predictors of glioma. It was observed clearly that multiple approaches are evolving and a few of them have also shown promising results. Depending on the type of gene alteration, a wide variety of methods may be applied in biomarker testing. Among the novel methods is next-generation sequencing (NGS) technology, enabling simultaneous detection of multiple alterations. The aim of this review is to discuss the predictive or potentially predictive genetic and epigenetic alterations of diffuse gliomas. The review concludes that NGS technology is the future and may likely replace, at least to some extent, the current routinely used methods, including FISH, IHC, and PCR-based methods, in clinical diagnostics.