Clinical phenotypes and radiological findings in frontotemporal dementia related to TARDBP mutations

It has been shown that different genes could be associated with distinctive clinical and radiological phenotypes of FTD. TARDBP gene has been described worldwide in few cases of FTD so its phenotype is still unclear. The objective is to study the clinical and radiological characteristics of TARDBP-related FTD. In the present study, we report clinical, neuropsychological and radiological features of five new Sardinian non-related cases of FTD carriers of the p.A382T TARDBP mutation. Furthermore, we reviewed non-related FTD cases with TARDBP mutations previously described in literature. The p.A382T missense mutation of TARDBP was present in the 21.7 \% of familial cases of our FTD cohort (5/23) and in no one of the sporadic patients. 3 of 5 patients showed a temporal variant FTD and 4/5 a predominant temporal involvement at MRI. The review of the literature of FTD cases with TARDBP mutations showed that in 5 of 16 cases, the clinical phenotype was consistent with temporal variant of FTD or semantic dementia (31 \%) and in 7 of 16 cases neuroimaging showed predominant temporal lobe involvement (43.7 \%). Our study further supports the pathogenetic role of TARDBP mutations in pure FTD and in the full spectrum of FTD/ALS. The presence of a predominant temporal lobe involvement in a high percentage of FTD mutated patients with a peculiar clinical pattern could be useful in the differential diagnosis with other forms of dementia/FTD both sporadic and familial.