TREM2 and Nasu-Hakola disease: Previous studies have shown that homozygous loss-of-function mutations in TREM2 are associated with the polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL; also called Nasu-Hakola disease) characterized by progressive early-onset dementia and bone lesions leading to fractures [3-5].