| Prevalence | Approximately 2–3 per 100,000 (representing ~20–30% of Frontotemporal Dementia cases) |
| Age at onset | Typically 55–65 years (range 40–80); slightly younger average onset than alzheimers |
| Sex | Slight male predominance in some series (M:F ~1.3:1) |
| Proportion of PPA | svPPA accounts for approximately 20–30% of all PPA cases |
| Proportion of FTD | Represents ~20–25% of Frontotemporal Dementia cases |
| Survival | Median 8–12 years from symptom onset; slower progression than behavioral variant FTD (bvFTD) |
| Family history | Most cases (~90%) have no significant family history of dementia or neurodegenerative disease [@landinromero2016] |
| Genetic mutations | Rarely associated with known FTD genes; occasional cases linked to: |
| Distribution | tdp-43 type C inclusions are most dense in **cortical layer 2** of the anterior and inferior temporal neocortex [@josephs2011], [@spinelli2017] |
| Frequency | 75–90% of svPPA cases show tdp-43 type C; remainder show tau] pathology (~5–10%, usually Pick's disease) or alzheimers pathology (~5%) |
| Anterior temporal lobe (ATL) atrophy | Bilateral but asymmetric, with the left ATL more severely affected in typical svPPA cases presenting with language symptoms |
| Specific subregions | The temporal pole, anterior fusiform gyrus, anterior inferior and middle temporal gyri, and anterior hippocampus are most severely affected |
| Databases | OMIMOrphanetClinicalTrialsPubMed |