DDX41 and myasthenia gravis: We prepared HexaHis-tagged peptides of T39MIR, H39MIR, and both 3XH39MIR and 4XH39MIR chimeric peptides, expressed them, purified them, and probed them for binding of anti-MIR Abs from human MG sera at a 1/100,000 dilution in dot blots of 2.5 μg of the purified His-tagged peptides.