A potential endophenotype for Alzheimer's disease: cerebrospinal fluid clusterin

Genome-wide association studies have associated clusterin (CLU) variants with Alzheimer’s disease (AD). However the role of CLU on AD pathogenesis is not totally understood. We used CSF and plasma CLU levels as endophenotypes for genetic studies to understand the role of CLU in AD. CSF, but not plasma, CLU levels were significantly associated with AD status and CSF tau/Aβ ratio, and highly correlated with CSF apolipoprotein E (APOE) levels. Several loci showed almost genome-wide significant associations including LINC00917 (p=3.98×10−7) and interleukin 6 (IL6, p=9.94×10−6, in the entire dataset and in the APOE ε4- individuals p=7.40×10−8). Gene-ontology analyses suggest that CSF CLU levels may be associated with wound healing and immune response which supports previous functional studies that demonstrated an association between CLU and IL6. CLU may play a role in AD by influencing immune system changes that have been observed in AD or by disrupting healing after neurodegeneration.