Below this threshold, each 0.1 mg/L increase in cystatin C was associated with a 13.84-fold elevation in stroke risk (OR = 13.84, 95% CI: 7.11–27.03; p < 0.001), whereas no significant association was observed above 1.24 mg/L (OR = 1.02, 95% CI: 0.78–1.26; p = 0.872). This evidence concerns the gene CST3 and Stroke.