2.4 Statistical analysis
SPSS 24.0 software was used for statistical analysis. Genetic balance was analyzed by Hardy-Weinberg equilibrium test. It was considered that P> 0.05 indicated that the genotype distribution conformed to the HW balance; Independent sample t test and chi-square test were performed for statistical analysis of clinical data and experimental results. P <0.05 represents statistical significance. The 95% confidence interval (CI) and odds ratio (OR) were used for risk analysis.