CD33 and Alzheimer disease: To evaluate the relationship between known AD risk loci, Chan et al. [9] recently conducted a protein quantitative trait analysis in monocytes and showed that the NME8 risk allele influences protein tyrosine kinase 2 β (PTK2B), the CD33 risk allele influences triggering receptor expressed on myeloid cells 2 (TREM2) and the TREM1 risk allele is associated with a decreased TREM1/TREM2 ratio.