MED12 and atrial fibrillation: However, a frameshift variant within MED12 (c.5285delA) was only found in cfDNA with an AF of 0.43%, and two MED12 frameshift variants which were previously found in the TIO patients in the discovery cohort (c.1080delT in TIO01 and TIO04, and c.4901delA in TIO02) were identified only in the PMT tissue of TIO05 with the AFs less than 1%.