TREM2 and Nasu-Hakola disease: TREM2 and TYROBP variants are found in patients with polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL) or Nasu–Hakola disease (NHD), an autosomal recessive hereditary disease characterized by early-onset dementia and bone cysts [203,204], concomitant with atrophy of temporal white matter and loss of myelin and axon in the brain [205], although some NHD patients with FTD-like syndromes are reported to lack bone phenotypes [163,176,206].