In this study, a commercially available enzyme‐linked immunosorbent assay (ELISA) kit was used to quantify levels of TMEM119 in the CSF of patients with AD, Lewy body diseases (LBD), ALS, frontotemporal lobar degeneration (FTLD), cerebral microangiopathy (CM), and in individuals with no known neurodegenerative diseases, to determine whether group differences in CSF TMEM119 may be observable. Here, TMEM119 is linked to cutaneous mastocytosis.