DNA extraction
In this study, peripheral blood was collected into ethylenediamine tetraacetic acid-containing tubes, and genomic deoxyribonucleic acid (DNA) was extracted from whole blood samples using the QIAamp DNA blood mini kit (Qiagen, GmbH, Hilden, Germany). DNA concentration was determined using a NanoDrop ND1000 spectrophotometer (Thermo Fisher Scientific Inc., Wilmington, DE, USA), and purity of the DNA was assessed based on the 260/280 nm absorbance ratio.