GAD1 and psychiatric disorder: Genome-wide association studies have shown that the level of DNA methylation, probably the best-studied epigenetic mark, is partly associated with nearby single-nucleotide polymorphisms (SNPs).1, 2, 3 An increasing number of SNPs have been associated with the pathogenesis of psychiatric disorders.4 In this context, genetic variants in various genes, such as COMT, BDNF, GAD1 or APOE,5, 6, 7, 8 are repeatedly highlighted.