Association of BIRC5 Gene Polymorphism with the Collateral Circulation and Severity of Large Artery Atherosclerotic Stroke

The collateral circulation near the cerebral artery occlusion can contribute to the relief of the symptoms and signs of stroke. Genetic factors play a decisive role in the difference in collateral circulation. Survivin, encoded by the baculoviral inhibitor of apoptosis (IAP) repeat-containing 5 gene (BIRC5), plays an important role in maintaining long-term endothelial integrity and homeostasis and as an angiogenic factor in the treatment of vascular diseases. We hypothesized that genetic variations in the BIRC5 gene may contribute to severity by influencing the collateral circulation. This study aimed at examining how the polymorphism of the BIRC5 gene correlated with the collateral circulation and severity of large artery atherosclerotic stroke.

This study enrolled 428 patients with large artery atherosclerotic stroke. There are no statistical differences in age, sex, social behavior, such as smoking and drinking, between the groups classified by the collateral circulation and by the severity of stroke (P > 0.01). Direct sequencing was performed for the genotyping of single nucleotide polymorphism (SNP) of BIRC5 (rs2071214). The enrolled patients were divided into several subgroups based on the collateral flow grading system from the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR), the results of the National Institutes of Health Stroke Survey (NIHSS) (6 as a threshold), and the score of the modified Rankin scale (mRS) (for the prediction of prognosis, 2 as a threshold). Differences among subgroups were identified through logistic regression.

The analysis of collateral circulation revealed the significant correlation of SNP of rs2071214 with the development of poor collateral circulation of large artery atherosclerotic stroke in the additive model (GG vs. AA, odds ratio (OR) = 3.592, 95% confidence interval (CI) = 1.410-9.150, and P=0.007) and the recessive model (GG vs. AA/GA, OR = 3.313, 95% CI = 1.420-7.727, and P=0.006). The analysis of stroke severity exposed the significant role of the SNP of rs2071214 in increasing stroke severity in the dominant model (GA/GG vs. AA, OR = 1.658, 95% CI = 1.017-2.703, and P=0.043) and the additive model (GA vs. AA, OR = 1.717, 95% CI = 1.021-2.888, and P=0.042). However, the analysis of the short-term outcome indicated that three genetic models were not associated with short-term outcomes in the additive model (GA vs. AA, P=0.815, GG vs. AA, and P=0.336), the dominant model (GA/GG vs. AA and P=0.589), and the recessive model (GG vs. AA/GA and P=0.342).

Our findings identified the SNP of rs2071214 of the BIRC5 gene as a risk factor for the poor compensatory ability of collateral circulation and a predictor of stroke severity in large artery atherosclerotic stroke, which suggested that the SNP of rs2071214 can serve as an innovative therapeutic target for patients with acute ischemic stroke.