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S058-4

Stereotypical behaviour and the associated white matter tracts in frontotemporal
dementia with the chromosome 9 open reading frame 72 gene expansions

Bonnie Yin Ka Lam

Department of Medicine and Therapeutics; Faculty of Medicine.; The Chinese University of Hong Kong, Hong
Kong

Content: The recent discovery of the genetic abnormality in the chromosome 9 open reading frame
72 (C9orf72) has changed the understanding of the pathophysiology of frontotemporal dementia. The
clinical features and white matter changes of behavioural-variant frontotemporal dementia (bvFTD)
cases carrying the C9orf72 gene expansions are poorly understood. The issue with inconsistence
neuropsychological and imaging findings in the C9orf72 literature will be reviewed. The association
between the clinical features and brain white matter changes in bvFTD with the C9orf72 gene
expansions is another area with limited findings. Brain white matter alterations in C9orf72 expansion
carriers showed significantly less pronounced frontotemporal tract changes compared to non-carriers.
In particular, the cingulum and uncinate fasciculus were associated with stereotypical behaviour and
these associations significantly differentiated expansion carriers from non-carriers.
Improvements on study design to fully investigate the biological and clinical characteristics of
C9orf72 expansion carriers will be proposed.