The behavioural variant of frontotemporal dementia with a C9orf72 expansion (C9-bvFTD) is characterised by early changes in social-emotional cognition that are linked to the loss of von Economo neurons (VENs).
Here we assessed [<sup>18</sup>F]AV-1451 binding in behavioral variant frontotemporal dementia due to a hexanucleotide repeat expansion in C9orf72, characterized by TDP-43 pathology.
Knowledge of the specific neuropsychological features associated with the C9ORF72 related bvFTD may aid in the early diagnosis of the disease as well as in targeting genetic testing.
The C9ORF72 expansion is the most common genetic etiology observed with bvFTD and the prevalence of the expansion is notably high among Finnish bvFTD patients.
We measured hypothalamic volume in 18 patients with bvFTD (including 9 MAPT and 6 C9orf72 mutation carriers) and 18 cognitively normal controls using a novel optimized multimodal segmentation protocol, combining 3D T1 and T2-weighted 3T MRIs (intrarater intraclass correlation coefficients ≥0.93).
MAPT carriers had the greatest change within left uncinate fasciculus (FA: -7.9%/yr, p < 0.001; MD: 10.9%/yr, p < 0.001); sporadic bvFTD and C9ORF72 carriers had the greatest change within right paracallosal cingulum (sporadic bvFTD, FA: -6.7%/yr, p < 0.001; MD: 3.8%/yr, p = 0.001; C9ORF72, FA: -6.8%/yr, p = 0.004).
We reviewed each individual item in the 1998 and FTDC criteria in 30 patients with bvFTD followed in a memory clinic (including 2 with the C9orf72 gene repeat expansion).
C9orf72 -associated FTLD most often presents with early-onset behavioral variant frontotemporal dementia with disinhibition as the prominent feature, with or without amyotrophic lateral sclerosis.
Behavioral variant frontotemporal dementia due to C9orf72 expansion displays some phenotypic heterogeneity and may be associated with hallucinations, parkinsonism, focal dystonia, and posterior brain atrophy.
Here we show that the large Lund pedigree with behavioral variant of frontotemporal dementia previously described with this disorder has an expansion in the recently described C9ORF72 locus on chromosome 9.