IFIH1 and myositis disease: Approximately half of enrolled participants had myositis-specific antibody (MSA) testing from various laboratories, with anti-NXP2 (aka MJ) being the most common antibody identified in 11/49 (22.4%) followed by anti-TIF1-γ (aka p155/140) in 7/53 (13.2%), anti-Mi2 in 6/55 (10.9%), anti-MDA5 in 4/51 (7.8%), and anti-Jo1 in 2/67 (3.0%) of participants tested (Table 1).