Its soluble form (sTREM2) can be measured in both CSF and blood, and elevated levels have been associated with AD in a variety of CSF (Piccio et al., 2016; Heslegrave et al., 2016) and plasma (Hu et al., 2014; Zhao et al., 2022) studies, hinting that the function of TREM2 is protective rather than detrimental for AD (Brown and St George-Hyslop, 2022; Nabizadeh et al., 2024). The gene discussed is TREM2; the disease is Alzheimer disease.