In conclusion, Parkinsonism was frequently associated with FTD but not ALS in a large Sardinian family, a finding reflected in the wider C9orf72 associated Sardinian ALS and FTD populations.
Presence of ALS is strongly indicative of a C9ORF72 expansion; a very early age at onset (<50 years), parkinsonism and oculomotor dysfunction are indicative of MAPT mutations; whereas hallucinations, CBDS and PNFA are indicative of PGRN mutations.
ALS was more frequent in C9ORF72 than in MAPT and PGRN patients; onset before age 50 and parkinsonism were indicative of MAPT mutations, whereas hallucinations were indicative of PGRN mutations; prioritization of genetic testing is thus possible.
The ALS/parkinsonism-dementia complex of Guam is a long latency disease with a diverse phenotypic expression characteristic of classical ALS, parkinsonism and dementia.
It was noticed in the mid-1950s that the incidence of ALS and parkinsonism--dementia complex (PDC) were much higher on Guam than anywhere else in the world.
Attention is drawn to the similarities between this disorder and other ethnic-geographic isolates, particularly the ALS-Parkinsonism-dementia complex of Guam.