Anti-signal recognition particle antibodies (anti-SRP), which are targeting signal recognition particle (SRP). Anti-SRP antibodies are mainly associated with, but are not very specific for, polymyositis. For individuals with polymyositis, the presence of anti-SRP antibodies are associated with more prominent muscle weakness and atrophy, and more cardiac manifestations.
Anti-Mi-2 antibodies, which are associated with a better prognosis.
^ abcKao, A. H.; Lacomis, D.; Lucas, M.; Fertig, N.; Oddis, C. V. (2004). "Anti-signal recognition particle autoantibody in patients with and patients without idiopathic inflammatory myopathy". Arthritis & Rheumatism50 (1): 209–215. doi:10.1002/art.11484. PMID14730618.edit