MAT1A and Anxiety: The liver‐specific suppression of Mat1a in naïve animals (Extended Data Figure S5a–c, Supporting Information) attenuated circulating and central SAM levels as well as brain RNA methylation (Extended Data Figure S5d,f, Supporting Information), leading to depressed cortical activity (Extended Data Figure S5g, Supporting Information) and anxiety‐like behaviors (Extended Data Figure S5h–j, Supporting Information).