Using a genome-wide methylation study, they found that the changes in DNA methylation of DNA-binding protein inhibitor ID-3 (ID3), glutamate receptor, ionotropic N-methyl-D-aspartate (NMDA) 1 (GRIN1), and tubulin polymerization promoting protein (TPPP) were predictors of depression in these children. Here, TPPP is linked to major depressive disorder.