The Right Temporal Variant of Frontotemporal Dementia Is Not Genetically Sporadic: A Case Series

J Alzheimers Dis. 2021;79(3):1195-1201. doi: 10.3233/JAD-201191.


Background: Right temporal variant frontotemporal dementia (rtvFTD) has been generally considered as a right sided variant of semantic variant primary progressive aphasia (svPPA), which is a genetically sporadic disorder. Recently, we have shown that rtvFTD has a unique clinical syndrome compared to svPPA and behavioral variant frontotemporal dementia.

Objective: We challenge the assumption that rtvFTD is a sporadic, non-familial variant of FTD by identifying potential autosomal dominant inheritance and related genes in rtvFTD.

Methods: We collected all subjects with a diagnosis of FTD or primary progressive aphasia who had undergone genetic screening (n = 284) and subsequently who had a genetic variant (n = 48) with a diagnosis of rtvFTD (n = 6) in 2 specialized memory clinics.

Results: Genetic variants in FTD related genes were found in 33% of genetically screened rtvFTD cases; including MAPT (n = 4), GRN (n = 1), and TARDBP (n = 1) genes, whereas only one svPPA case had a genetic variant in our combined cohorts. Additionally, 4 out of 6 rtvFTD subjects had a strong family history for dementia.

Conclusion: Our results demonstrate that rtvFTD, unlike svPPA, is not a pure sporadic, but a heterogeneous potential genetic variant of FTD, and screening for genetic causes for FTD should be performed in patients with rtvFTD.

Keywords: Dementia; GRN; MAPT; TARDBP; frontotemporal dementia; frontotemporal lobar degeneration; genetic; right temporallobe.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aphasia, Primary Progressive / genetics
  • Aphasia, Primary Progressive / pathology
  • DNA-Binding Proteins / genetics
  • Female
  • Frontotemporal Dementia / genetics*
  • Frontotemporal Dementia / pathology
  • Functional Laterality
  • Genetic Testing
  • Genetic Variation / genetics
  • Gyrus Cinguli / pathology
  • Humans
  • Male
  • Middle Aged
  • Progranulins / genetics
  • tau Proteins / genetics


  • DNA-Binding Proteins
  • GRN protein, human
  • MAPT protein, human
  • Progranulins
  • TARDBP protein, human
  • tau Proteins