Humans with TREM2 deficiency develop the Nasu-Hakola syndrome, characterised by dementia and bone cysts [106], while several Trem2 KO mice show various – sometimes contradictory – phenotypes due to alterations of expression in other genes beyond Trem2 (e.g. Trem1L) in some models [107]. This evidence concerns the gene TREM2 and dementia.