16 March 2026
: Case report 
Fatal Cardiomyopathy Secondary to Seronegative Immune-Mediated Necrotizing Myopathy: A Case Report
Challenging differential diagnosis, Rare disease, Rare coexistence of disease or pathology
Benjamin D. Lueck ABCDEF 1, Alyssa K.W. Maclean ABCDEF 1, Georges El Hasbani ABCDEF 2, Andrew J. Layman CDE 3, Floranne C. Ernste CDEF 2, Courtney A. Arment ABCDEFG 2*DOI: 10.12659/AJCR.951603
Am J Case Rep 2026; 27:e951603
Table 1 Results of testing for myositis-specific and myositis-associated antibodies.
| Antibody | Result at presentation | Result at month 9 | Reference range |
|---|---|---|---|
| anti-Jo-1 | <20 units | <20 units | <20 units |
| anti-PL-7 | Negative | Negative | Negative |
| anti-PL-12 | Negative | Negative | Negative |
| anti-EJ | Negative | Negative | Negative |
| anti-OJ | Negative | Negative | Negative |
| anti-SRP | Negative | Negative | Negative |
| anti-Mi-2 | Negative | Negative | Negative |
| anti-TIF-1gamma | <20 units | <20 units | <20 units |
| anti-MDA-5 (CADM-140) | <20 units | <20 units | <20 units |
| anti-NXP-2 (P140) | <20 units | <20 units | <20 units |
| anti-PM/SCL-100 | <20 units | <20 units | <20 units |
| anti-Ku | Negative | Negative | Negative |
| anti-SS-A 52kD IgG | <20 units | <20 units | <20 units |
| anti-U1 RNP | Negative | Negative | Negative |
| anti-U2 RNP | Negative | Negative | Negative |
| anti-U3 RNP (fibrillarin) | Negative | Negative | Negative |
| anti-SAE1* | <20 units | <20 units | |
| Testing was commercially available and completed through LabCorp. * Indicates result included in the MyoMarker 3 Plus Profile but not in the MyoMarker 3 Profile (both, LabCorp). Jo-1 – histidyl–transfer RNA (tRNA) synthetase; PL-7 – threonyl–tRNA synthetase; PL-12 – alanyl–tRNA synthetase; EJ – glycyl–tRNA synthetase; OJ – isoleucyl–tRNA synthetase; SRP – signal recognition particle; Mi-2 – Mi-2 nucleosome remodeling–deacetylase complex protein; TIF-1γ – transcription intermediary factor 1 gamma; MDA-5 – melanoma differentiation–associated gene 5 (also known as CADM-140); NXP-2 – nuclear matrix protein 2 (also known as P140); PM/Scl-100 – polymyositis/scleroderma 100-kDa protein; Ku – Ku autoantigen; SS-A 52 kD IgG – Sjögren syndrome–related antigen A 52-kDa immunoglobulin G; U1 RNP – U1 ribonucleoprotein; U2 RNP – U2 ribonucleoprotein; U3 RNP – U3 ribonucleoprotein (fibrillarin); SAE1 – small ubiquitin-like modifier–activating enzyme 1. | |||