To this end, single cell suspensions from patient-matched MM and UFs, including MED12 mutation-positive and MED12 mutation-negative tumors (Supplemental Fig. S4), were plated and processed for DNA fiber analysis within 3 days in order to ensure retention of MED12-mutant cells that are otherwise lost within the first several passages in culture31. Here, MED12 is linked to Miyoshi myopathy.