The markers available include S100, GFAP, ATRX, olig-2, EMA, enolase, neurofilament, IDH1, p53, and IN1-1, but most countries with immunohistochemistry are still lacking stains such as GAB-1 necessary for proper classification of medulloblastoma and YAP-1 useful in both medulloblastomas and ependymomas, ZFTA which is used in the diagnosis of supratentorial ependymomas, and H3 K27 which is important in diffuse midline gliomas. The gene discussed is OLIG2; the disease is ependymoma.