IDH1 and oligodendroglioma: The other samples were astro cytomas (n = 22, 15%), anaplastic astrocytomas (n = 25, 17%), oligodendrogliomas (n = 3, 2%), anaplastic oligodendrogliomas (n = 4, 3%), oligoastrocytomas (n = 12, 8%), and anaplastic oligoastrocytomas (n = 20, 14%) (Figure 3).Out of the 147 FFPE samples which met the selection criteria, DNA extraction failed for one sample, while an IDH1/2 result was successfully obtained by the PCR test in 91% of cases (133/146).