SIDT2 and depressive symptom measurement: In order to analyze the link between the SNPs (rs1784042 and rs17120425) in the SIDT2 gene and gene expression, we used the online resources: the Genotype-Tissue Expression (GTEx) project (https://www.gtexportal.org/home/), the Netherlands Study of Depression and Anxiety (NESDA) and the Netherlands Twin Registry (NTR) Conditional Expression Quantitative Trait Loci (eQTL) catalog (https://eqtl.onderzoek.io/) and the RegulomeDB (http://www.regulomedb.org/).