TREM2 and Nasu-Hakola disease: Null mutations in either TREM2 or TYROBP genes were reported to cause a rare form of early-onset neurodegenerative disorder known as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), or Nasu–Hakola Disease (NHD) [18,19,20].