Rare TBK1 variants in patients with frontotemporal dementia and amyotrophic lateral sclerosis in a Chinese cohort.

Background: The TANK-Binding Kinase 1 ( TBK1 ) gene has recently been identified as the third or fourth most frequent cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The aim of this study was to assess the genetic contribution of TBK1 in a Chinese cohort.

Methods: A total of 270 cases with ALS, FTD, or their combination were recruited into this study. All the coding exons of TBK1 and intron-exon boundaries were sequenced using Sanger sequencing. The frequency of TBK1 variants and the correlation with clinical phenotypes were analyzed.

Results: A novel mutation (c.1959_1960insGT, p.E653fs) was identified in a sporadic case with semantic dementia, secondarily developing ALS. Another novel variant (c.2063_2064delTT, p.L688Rfs*14) was found in an ALS-FTD family. Totally, the TBK1 variants could only account for 0.7% of cases.

Conclusions: This study enlarges the genetic and phenotypic spectrum of TBK1 mutation in a Chinese cohort. Our data indicates that TBK1 mutation is not a common cause for ALS and FTD in Chinese patients.