Tau exon 10 +16 mutation FTDP-17 presenting clinically as sporadic young onset PSP.

The authors describe a case of clinically diagnosed young onset progressive supranuclear palsy (PSP) with symptom onset at 40 years of age and no family history of neurodegenerative disease. There was no history of falls during the first year of symptoms. Genetic analysis identified this patient as having a tau exon 10 +16 mutation (MAPT, IVS10, C-U, +16). Neuropathologic examination confirmed the genetic diagnosis of frontotemporal dementia. An age at onset younger than 50 years combined with the absence of early falls may indicate the possibility of a tau mutation in clinically diagnosed PSP.