Importantly, CSF sTREM2 levels were – in contrast to CSF markers of Aβ and tau pathology – not associated with ApoE4-carriage, confirming previous evidence that CSF sTREM2 concentrations [43] or PET-assessed microglial activation [44] are per se unrelated to ApoE4-associated genetic AD risk. This evidence concerns the gene APOE and Alzheimer disease.