CCR5 and snowflake vitreoretinal degeneration: For instance, a 32 base-pair deletion in CCR5 (Chemokine C-C motif receptor 5) gene (Δ32 polymorphism) is considered to exert a protective effect against CE stroke as it has lower frequency in this subtype (OR, 0.4; 95% CI, 0.24-0.79; p=0.008) than in LAA, SVD or cryptogenic strokes [90].