ATRX and astrocytoma (excluding glioblastoma): 68% of grade II astrocytomas harbored low ATRX expression, similar to the Jiao's result from exon sequencing data, whereas the incidence of low ATRX expression was only 50% in anaplastic astocytomas and 33% in secondary glioblastomas, and up to 43% of primary glioblastomas contained low ATRX expression.