SPP1 and frontotemporal dementia: Interestingly, OPN is elevated in other neurodegenerative disorders including multiple sclerosis (MS), Alzheimer’s disease, Parkinson’s disease, and frontotemporal dementia (Braitch et al. 2008; Chabas et al. 2001; Comabella et al. 2005; Comi et al. 2010; Iczkiewicz et al. 2006; Maetzler et al. 2007; Mattsson et al. 2008; Wirths et al. 2010).