Statistical analysis
The chi-squared test was used to evaluate the Hardy-Weinberg equilibrium or allele frequencies of all SNPs. Unconditional logistic regression was conducted to calculate the adjusted odds ratio (OR) and 95% confidence intervals (95% CI). The association analysis was tested using logistic regression analysis with Plink under additive, dominant, and recessive models. The test of significance was set at two-tailed P = 0.05.