Prevalence of immunological diseases in a Finnish frontotemporal lobar degeneration cohort with the C9orf72 repeat expansion carriers and non-carriers.

Recent studies have suggested a role for immune dysregulation behind the etiology of frontotemporal lobar degeneration (FTLD). Here, we have investigated the prevalence of immunological diseases in FTLD (N = 196) with and without the C9orf72 repeat expansion, Alzheimer's disease (AD) (N = 193) and not cognitively impaired (NCI) subjects (N = 92). The prevalence was 16.3% in FTLD, 13.5% in AD and 15.2% in NCI. Although differences between the groups did not reach statistical significance, the frequency of immunological diseases was the highest in FTLD without the C9orf72 expansion (22/117, 18.8%) and the lowest in FTLD with the expansion (6/56, 10.7%), suggesting that the C9orf72 expansion possibly influences immunological pathways in FTLD.