General characteristic of the two-stage GWAS study subjects.

at-Test was used to compare means between the first and the second stages. bChi-square test was used to compare the differences in categorized variables.a. 采用t检验（t-test）对第一阶段与第二阶段的均值进行比较。b. 采用卡方检验（chi-square test）对分类变量的组间差异进行比较。