TREM2 and Nasu-Hakola disease: Biallelic loss-of-function mutations in TREM2 or TYROBP (encoding its cytoplasmic adaptor molecule, also known as DAP12) cause Nasu-Hakola disease, also known as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL).