BCOR and neoplasm: Targeted reverse transcription–PCR (RT–PCR) of an intron-spanning segment of the BCOR transcript (exons 14 and 15; Supplementary Table 3) confirmed expression of the mutant allele in all ITD-positive tumours tested (n=4), including two from female patients, suggesting that the mutant allele had not been silenced through X-inactivation (Fig. 2a).