What is the difference between P155/140 and TIF1-γ antibodies on the ARUP myositis panel? Are these essentially the same antibody or do they provide different clinical information?

TIF1g is the name of the protein itself, whereas "p155/140" refers to the IP (immunoprecipitation) finding of 2 distinct bands at 155 kDa (TIF1g) and 140 kDa (TIF1a), indicative of an anti-TIF1g antibody response. Until recently, ARUP (like most commercial laboratories) used immunoblotting, as it is...