Targeted high-throughput sequencing identifies a TARDBP mutation as a cause of early-onset FTD without motor neuron disease.

Targeted high-throughput sequencing of many amyotrophic lateral sclerosis (ALS) and fronto-temporal dementia (FTD) genes in parallel has the potential to reveal novel ALS- and/or FTD-phenotypes and to provide missing links on the ALS-FTD continuum. For example, although the 43-kDa transactive response DNA binding protein is the major pathologic hallmark linking ALS and FTD, mutations in the gene encoding 43-kDa transactive response DNA binding protein (TARDBP) have been appreciated only as a cause of ALS-phenotypes, but not yet of pure FTD. Thus, the genetic link is not yet well substantiated that TARDBP mutations can cause the full spectrum of the ALS-FTD continuum. High-throughput sequencing of 18 ALS and FTD genes in an index patient presenting with early-onset pure (behavioral) FTD and a positive family history for ALS revealed an established TARDBP mutation, A382T. This finding demonstrates that a TARDPB mutation can cause early-onset pure FTD without evidence for ALS even in advanced FTD disease stages. Moreover, it indicates that TARDPB screening might be considered even in young patients with "pure" neuropsychiatric disturbances and without evidence of neurodegenerative disease in the parental generation.