TREM2 and Alzheimer disease: Interestingly, CLCN2 shows co-expression with TREM2 which, other than being an AD risk gene, is known to cause leukoencephalopathy in PLOSL (polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy), also known as Nasu-Hakola disease.