TREM2 and Alzheimer disease: In relation to AD traits, the trans pQTL in MS4A4A (rs1530914) for TREM2 levels is in high LD with a TREM2 variant (rs1582763, r2 ∼ 0.9) associated with AD in apolipoprotein E (APOE) ε4 carriers and family history of AD.3, 42