A polymorphism in the cystatin C promoter region is not associated with an increased risk of AD.

Cystatin C is a potent cysteine proteinase inhibitor that binds to and regulates proteolytic activities of cysteine proteinases including cathepsins.1 Current evidence suggests a role for cystatin C in the pathogenesis of various amyloidoses, including AD. A mutation at position 68 of the cystatin C gene is associated with one of the familial cerebral angiopathies (HCHWA-I).2 Furthermore, immunohistochemical studies in brains of patients with AD and cerebral amyloid angiopathy have demonstrated colocalization of cystatin C and β-amyloid (Aβ) in parenchymal and vascular amyloid deposits.3 Recently, a polymorphic site in the promoter region and the coding region of the cystatin C gene ( CST3–1 ) was reported to confer a greater risk for carriers of the CST3–1 G/G genotype to develop AD.4,5⇓ To further investigate this proposed association, we determined CST3–1 genotypes in patients with AD and a corresponding control group of nondemented subjects of similar age and ethnic background. In addition, we analyzed the segregation of the Apolipoprotein E ( APOE ) allele and CST3–1 in the same cohort. The cohort included 468 individuals from the Memory Clinics …