TYROBP and frontotemporal dementia: Homozygous mutations in TREM2 or its intracellular signaling partner DAP12 are causal for Nasu-Hakola disease (NHD), which is associated with bone cysts and an early-onset dementia (Paloneva et al., 2000, Paloneva et al., 2002), while a frontotemporal dementia (FTD)-like syndrome without bone dysfunction has also been described in patients carrying certain TREM2 mutations (Chouery et al., 2008, Giraldo et al., 2013, Guerreiro et al., 2013b).