CLU and Alzheimer disease: Some of these highest quality biomarker candidates have been subjected to an iterative process of verification and assay development: plasma α-2-macroglobulin and complement factor H, although elevated in AD subjects, compared to controls had low sensitivity (39–49%), though high specificity (80%, [6]), whereas plasma clusterin (amyloid chaperone protein) increase in AD subjects has yet to be confirmed in other studies [8,14].