Homo sapiens
Protocols: Genomic DNA was extracted from the whole blood of children using a Blood DNA Extraction Kit (Tiangen Biotech, China), then treated with EpiTect Fast DNA Bisulfite Kit (QIAGEN, Germany) for bisulfite conversion. The converted DNA was PCR amplified with primer sequences designed to cover the CpGs in two promoter regions: each region included near 1,000 bp centering around the transcription start sites (TSSs) of SLC22A18. The PCR products were purified and used for DNA library preparation. According to the manufacturer's protocol, the library was prepared with the KAPA HTP Library Preparation Kit (KAPA Biosystems, USA).