IRF4 and cancer: For the ‘BCAT1 replicate rule’, a specimen was deemed positive when at least one PCR replicate was positive for methylation in either IKZF1 or IRF4, or at least two PCR replicates were positive for methylation in BCAT1. With this rule, the false-positive rate for cancer was significantly reduced from 9.9% (81/820) to 5.9% (48/820, 95% CI4.4–7.8, p < 0.0001), while the sensitivity was not significantly affected; 73.9% (136/184, 95% CI 67.1–79.7) versus 71.2% (131/184, 95% CI 64.1–77.6; p = 0.562).