| Patient no. | Age at biopsy (years) | COX deficiency | RRF | Lipid accumulation | Other pathology of skeletal muscle fibres | Abnormal MT* | Lipid droplets | Miofibrile loss | Cytoplasmic bodies | Concentric laminated bodies |
| 1 | 2 | ++ | − | + | Variability of diameter | + | − | − | − | − |
| 2 | 7 | ++ | − | ++ | Not found | +/− | + | + | − | − |
| 3 | 12 | ++ | − | ++ | Mild variability of diameter | − | + | + | − | − |
| 4 | 3.5 | NA | − | NA | Not found | + | − | + | − | − |
| 5 | 4 | NA | − | + | Not found | − | − | + | − | − |
| 6 | 6.5 | ++ | − | − | Variability of diameter | ++ | − | − | + | − |
| 7 | 3.75 | ++ | − | + | Not found | − | + | − | − | − |
| 8 | 3 | NA | − | − | Not found | NA | NA | NA | NA | NA |
| 9 | 3 | + | − | ++ | Not found | + | − | − | − | − |
| 10 | 2.5 | ++ | − | + | Mild variability of diameter | ++ | + | + | − | + |
| 11 | 10 | ++ | − | + | Variability diameter, fibre type grouping | − | + | − | − | − |
| 12 | 1.75 | + | − | + | Not found | +/− | + | + | − | − |
| 13 | 2 | ++ | − | ++ | Predominance of type I fibres | ++ | + | − | − | − |
| 14 | 3 | ++ | − | − | Mild interstitial fibrosis | + | + | − | − | − |
| 15 | 2.75 | ++ | − | + | Predominance of type I fibres | − | − | + | − | − |
| 16 | 0.75 | ++ | − | + | Predominance of type I fibres | ++ | + | − | − | − |
| 17 | 1.5 | + | − | ++ | Variability of diameter | + | − | + | − | − |
| 18 | 1.5 | + | − | ++ | Not found | + | + | − | − | − |
| 19 | 1.5 | + | − | ++ | Mild variability of diameter | − | + | − | − | − |
| 20 | 1 | ++ | − | − | Mild variability of diameter | − | − | − | − | − |
| 21 | 1.5 | + | − | ++ | Mild variability of diameter | NA | NA | NA | NA | NA |
Light microscopy and electron microscope findings: +/− mild changes; + moderate changes; ++ severe changes; − no changes; *Mitochondrial (MT) ultrastructure abnormalities: +++: increase in mitochondrial number, changes in size, shape, and presence of electron dense inclusions; ++: increase in mitochondrial number, variation in size and shape; +: increase in mitochondrial number, slight variation in size and shape; +/−: slight increase in mitochondrial number.
COX, cytochrome c oxidase; NA, not analysed; RRF, ragged red fibre.