Genotyping and quality control
All participants underwent a microarray assay, using the Illunina HumanCore BeadChip kit (Illumina, San Diego, CA, USA). We filtered out poor quality single nucleotide polymorphisms (SNPs) and samples, which were defined as SNPs with a monographic genotype, a Hardy-Weinberg equilibrium p < 10-6, a call rate <95%, and a minor allele frequency <1%. After quality control, the remaining 264,283 SNPs were used in subsequent analysis.