Researchers have discovered a new opportunity to develop bio markers for brain disorders. New findings suggest that serine/theronine (o-linked) glycoproteins in the brain are uniquely vulnerable to epilepsy-causing SLC35A2 mutations. This work is focused on the identification and monitoring of children with SLC35A2-associated epilepsy. The findings can be applied in several settings, including the use of Western blot and immunofluorescence analysis of t‑aGalNAc levels from brain biopsies as diagnostic tools, as well as the development of highly sensitive biomarker assays using mass spectrometry to measure brain‑specific t‑aGalNAc in CSF, plasma or serum, urine, and extracellular vesicles.