Table 1.
Characteristics of anti-TIF1γ, anti-NXP2, and anti-HMGCR myositis.
| Anti-TIF1γ dermatomyositis (DM) | Anti-NXP2 DM | Anti-HMGCR immune-mediated necrotizing myopathy | |
|---|---|---|---|
| Year of discovery of the aAb | 2006 (49, 57) | 1997 (64) | 2010 (65, 66) |
| Frequency of cancer association in adults | 60–80% (22, 52, 59) | 24–37.5% (60, 61, 67) | 12.9–36% (56, 68, 69) |
| Clinical features | |||
| Skin involvement | Extensive cutaneous signs | Mild skin involvement | Generally not |
| Poikiloderma | Frequency of calcinosis | ||
| Psoriasis-like lesions | |||
| Scaly erythema of the scalp | |||
| No calcinosis | |||
| Muscular involvement | Mild weakness | Mild to severe weakness | Mild to severe weakness |
| Myalgia | |||
| Frequency of distal weakness | Inconstant dysphagia | ||
| Frequent dysphagia | Myalgia, muscle atrophy | ||
| Frequent dysphagia mild to severe | |||
| Other characteristics | Peripheral edema | Peripheral edema | High frequency of statin exposure (65, 66, 71) |
| Decreased risk of Raynaud phenomenon, arthralgia, and interstitial lung disease (60) | Low frequency of interstitial lung disease (61, 70) | ||
| Histological pattern | Dense C5b-9 deposits on capillaries | Perivascular inflammation | Necrosis |
| Presence of vacuolated fibers | Perifascicular atrophy | Muscle fiber regeneration | |
| Overexpression of MHC class I | Necrosis in patient with peripheral edema (70) | Atrophic fibers | |
| Perifascicular atrophy | Little or no inflammatory infiltration C5b-9 deposition (13, 72) | ||
| Necrotic/regenerating fibers (59) | |||
| Target of the aAbs | |||
| Name | Transcriptional intermediary factor 1 gamma | Nuclear matrix protein 2 or microrchidia 3 (MORC3) | 3-hydroxy-3-methylglutaryl-coenzyme-A-reductase |
| Protein expression | Ubiquitous | Ubiquitous | Ubiquitous |
| Immune cells at high level | Liver | ||
| Subcellular locations | Nucleus | Nucleus | Endoplasmic reticulum |
| Cytosol in part | Peroxisome | ||
| Role | TGFβ pathway | Chromatin remodeling | Limiting enzyme for cholesterol synthesis and other mevalonate-dependent pathways (81–83) |
| Mitosis | DNA repair | ||
| Embryonic development | Epigenetic regulation | ||
| DNA repair | Cell regulation | ||
| Erythropoiesis | Activation of p53 | ||
| Innate immunity | Calcium homeostasis | ||
| (73–76) | Bone remodeling (77–80) | ||