Pure Early-Onset Dementia Without Bone Cysts, is , as the name suggests, a disorder of progressive early onset dementia. Mutations in the TREM2 gene have been shown to be causal for this condition. However, affected patient do not show any osseous changes, which markes the difference from the condition, Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy.