Auto-antibodies in dermatomyositis and polymyositis with corresponding clinical spectrum
| Autoantibodies | Antibody target | Frequency in polymyositis/ADM/JDM % | Frequency of ILD in adult/juvenile myositis % | Clinical spectrum | |
| In adulthood | In childhood | ||||
| Myositis-specific autoantibodies (MSA) | |||||
| Anti-tRNA synthetase | 29/20/5 | ||||
| Anti-Jo1 (PL1) | Histidyl-ARS | 21/11/<3 | 66/63 | Arthralgia, fever, RP, mechanic's hand, puffy finger | Arthralgia, fever, RP, mechanic's hand, sclerodactyly |
| Anti-PL7 | Threonyl-ARS | 5/2/<1 | 84/63 | ||
| Anti-PL12 | Alanyl-ARS | 2/3/<1 | |||
| Anti-KS | Asparaginyl-ARS | <1 | |||
| Anti-OJ | Isoleucyl-ARS | <1 | |||
| Anti-EJ | Glycyl-ARS | <1 | |||
| Anti-SC | Lysyl-ARS | <1 | |||
| Anti-JS | Glutaminyl-ARS | <1 | |||
| Anti-YRS (Ha) | Tyrosyl-ARS | <1 | <1 | ||
| Anti-Zo | Phenylalanyl-ARS | <1 | |||
| Dermatomyositis specific autoantibodies | |||||
| Anti-Mi2 | Nucleosome remodelling deacetylase complex | 1/9/4–10 | 4/0 | Classical DM without extramuscular involvement | Mild or moderate JDM |
| Anti-NXP2 (MJ, p140) | Nuclear matrix protein 2 | 10/0–3/12–25 | 0/25 | DM without extramuscular involvement, calcinosis | Mild or moderate JDM |
| Anti-MDA5 (CADM-140) | Melanoma differentiation-associated gene encoding RNA helicase | <1/14–46/7 | Europe: 60; Asia: 90/Europe:19; Asia: 53 | Amyopathic DM, severe cutaneous ulcers, rapidly progressive ILD | Severe cutaneous ulcers, RP-ILP, mediastinal emphysema |
| Anti-TIF1γ (p155/140) | Transcriptional intermediary factor 1γ | <1/10–30/14–29 | <10/3 | Cancer associated DM in 78% of cases | Mild or moderate JDM |
| Other MSA | |||||
| Anti-SRP | Signal recognition particle | 5/1/<3 | 15/0 | Necrotising myopathy | Severe JPM |
| Anti-HMGR (200–100) | 3-hydroxy-3-methylglutaryl-coenzyme A reductase | 10/<1/unknown | Unknown | Necrotising myopathy | Unknown |
| Anti-SAE | Small ubiquitin-like modifier activating enzyme | <1/5–10/1–9 | DM | Unknown | |
| Myositis-associated autoantibodies | |||||
| Anti-Ro/Ssa | RNP complexes with small cytoplasmic RNAs (hY-RNA) | 12/13/0 | |||
| Anti-U1RNP | 70 kDa, A and C polypeptides of U1 snRNP | 5/6/6 | 7 | DM, fever, RP, sclerodactyly | |
| Anti-PM/Scl (75 and 100 kDa) | PM/Scl complex encompassing C1D, PM-Scl-100 and PM-Scl-75 proteins of the human exosome | 6/9/4 | 38 | Fever, RP, sclerodactyly | |
| Anti-Ku | 80 and 70 kDa DNA binding dimeric protein | 2/1/0 | 27 | Fever, RP, sclerodactyly | |
ADM: adult dermatomyositis; JDM: juvenile dermatomyositis; ILD: interstitial lung disease; SRP: signal recognition particle; ARS: aminoacyl-tRNA synthetase; RP: Raynaud's phenomenon; DM: dermatomyositis specific rash; RP-ILP: rapidly progressive ILD; JPM: juvenile polymyositis.