Pick’s Disease Pathology of a Missense Mutation of S305N of Frontotemporal Dementia and Parkinsonism Linked to Chromosome 17: Another Phenotype of S305N

We report the second phenotype of frontotemporal dementia and parkinsonism linked to chromosome 17 with S305N similar to Pick's disease pathology in two brothers. The brain of the older brother showed macroscopic atrophy compatible with Pick's disease, and subsequent tau gene analysis revealed heterozygous S305N mutation in exon 10 of the tau gene. Round-shaped neuronal inclusions similar to Pick's bodies were positive for phosphorylated serine 262 as well as other anti-tau antisera, which is different from immunoexpression of Pick's bodies. Ultrastructurally, these neuronal inclusions consisted of straight, randomly orientated fibrils measuring approximately 10-20 nm in width and 60-600 nm in length. This ultrastructural profile is similar to that of the first case of S305N. S305N reported here can cause another phenotype closely resembling Pick's disease.