C9orf72 and behavioral variant of frontotemporal dementia: The fact that we overall identified significant association between pathogenic expansions and a diagnosis of bvFTD and Central/Northern European ancestry—findings in line with previous reports8,10,13,20,30, –, 34—suggests that C9orf72 expansions might serve as useful genetic fingerprint to define subpopulations of FTLD (figure 3).