| | ALS phenotypes | C9ORF72 ALS | ALS-FTD | sALS | SOD1 ALS |
| | C9ORF72 ALS | — | — | — | — |
| | ALS-FTD | Cistaro et al.’s C9ORF72 study found (in C9ORF72 patients) hypometabolism in the left temporal cortex compared to ALS-FTD patients [18]. No hypermetabolism was identified anywhere. | — | — | — |
| | sALS | Cistaro et al.’s C9ORF72 ALS study also included a comparison with sALS patients. In C9ORF72 ALS, hypermetabolism was seen in the midbrain, bilateral occipital cortex, globus pallidus, left middle temporal cortex, and left inferior temporal cortex compared to sALS. Hypometabolism was seen in bilateral anterior and posterior cingulate cortices, insula, caudate, thalamus, left frontal cortex, and superior temporal cortex [18]. A recent study by De Vocht et al. demonstrated lower metabolism in the perirolandic region and increased metabolism in the brainstem [33]. | Cistaro et al. reported that ALS-FTD had hypermetabolism in the bilateral occipital cortex, left precentral cortex, left postcentral cortex, and superior temporal gyrus while hypometabolism was in the right orbitofrontal, prefrontal, anterior cingulate, and insular cortices when compared to sALS [18]. | — | — |
| | SOD1 ALS | De Vocht et al. observed C9ORF72 hypometabolism in the thalamus, posterior cingulate gyrus, postcentral gyrus, and precentral gyrus compared to SOD1 ALS. Hypermetabolism in the brainstem, lentiform nucleus and cerebellum was observed compared to SODI ALS [33]. | — | Canosa et al.’s SOD1 study revealed (in sALS compared to SOD1) hypometabolism in the right precentral gyrus, right medial frontal gyrus, right paracentral lobule, and bilateral postcentral gyrus. No hypermetabolism was identified [22]. De Vocht et al. revealed no difference between the groups [33]. | — |
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