Summary of muscle biopsy features stratified by anti-cN1-A antibody status
| Biopsy feature | Anti-cN-1A positive (%) | Anti-cN-1A negative (%) | OR (95% CI) | p Value |
|---|---|---|---|---|
| Excess COX-deficient fibres (n=185) | 53/61 (86.9) | 89/124 (71.8) | 2.61 (1.13 to 6.03) | 0.025* |
| Ragged red fibres (n=164) | 30/55 (54.6) | 54/109 (49.5) | 1.22 (0.64 to 2.34) | 0.545 |
| Atrophic fibres (n=176) | 59/69 (85.5) | 98/107 (91.6) | 0.54 (0.21 to 1.41) | 0.209 |
| Inflammation (n=290) | 94/96 (97.9) | 193/194 (99.5) | 0.24 (0.02 to 2.72) | 0.251 |
| MHC I upregulation (n=198) | 67/69 (97.1) | 124/129 (96.1) | 1.35 (0.26 to 7.15) | 0.724 |
| Necrosis (n=136) | 40/50 (80.0) | 61/86 (70.9) | 1.64 (0.71 to 3.78) | 0.246 |
| Mononuclear infiltrate (n=224) | 72/74 (97.3) | 143/150 (95.3) | 1.76 (0.36 to 8.70) | 0.487 |
| Invasion of non-necrotic fibres (‘partial invasion’) (n=95) | 21/30 (70.0) | 48/65 (73.9) | 0.83 (0.32 to 2.15) | 0.696 |
| Rimmed vacuoles (n=257) | 77/88 (87.5) | 143/169 (84.6) | 1.27 (0.60 to 2.72) | 0.533 |
| Protein deposits† (n=128) | 24/44 (54.6) | 53/84 (63.1) | 0.70 (0.34 to 1.47) | 0.349 |
| Microfilaments‡ (n=81) | 9/24 (37.5) | 24/57 (42.1) | 0.83 (0.31 to 2.20) | 0.700 |
Figures in brackets represent within antibody group percentages. n represents data available for analysis per variable (of a total of 311). p Value is derived from logistic regression.
*Adjusted (for age at disease onset, gender and comorbidities) OR 2.60, 95% CI 1.11 to 6.12, p=0.028. Adjusted (additionally for age at biopsy) OR 2.80, 95% CI 1.17 to 6.66, p=0.020.
†Includes amyloid (Congo Red or immunofluorescence), p62 (immunofluorescence) and TDP-43 (immunofluorescence).
‡15–21 nm tubulofilaments identified by electron microscopy.
Anti-cN-1A, anticytosolic 5′-nucleotidase 1A; COX, cytochrome oxidase; MHC, major histocompatibility complex.