No association between the cystatin C gene polymorphism and Alzheimer's disease: a case-control study in an Italian population.

Cystatin C is an amyloidogenic protein found together with beta-amyloid in cerebral arteriolar walls of both patients with Alzheimer's Disease (AD) and conghopilic amyloid angiopathy. Several findings implicate cystatin C in the pathogenesis of vascular diseases. Recent genetic association studies proposed cystatin C gene (CST3) as a susceptibility factor for AD, although other reports did not replicate this finding. We conducted a case-control study including 192 probable AD cases and 192 age- and sex-matched controls to test the association between CST3 and AD. Possible interaction between CST3 and age at onset of AD or apolipoprotein E (APOE) was also examined. No significant differences in CST3 genotype or allele frequencies between cases and controls was observed, while the risk of AD increased in subjects carrying the APOE epsilon4 allele (OR 3.5, 95% CI [2.1-5.9]). There was no interaction between CST3 with age or APOE. Our findings do not support a role of CST3 gene in Italian sporadic AD.