CST3 and early-onset autosomal dominant Alzheimer disease: It has been shown that Cys C co-deposits with Aβ in Alzheimer’s disease patients’ brains [22] and the association between cystatin C and Aβ demonstrate a specific, saturable, and high-affinity binding between cystatin C and both Aβ1–42 and Aβ1–40 [23].