TREM2 and frontotemporal dementia: However, the microglial lipid receptor TREM2 [40, 46] was increased in frontal grey matter (F = 12.5, p = 0.0002) and parietal white matter (F = 33.6, p < 0.0001) of both FTD-GRN and FTD-C9orf72 cases, and frontal white matter of FTD-GRN cases (F = 4.7, p = 0.019).