Thus, (1) having adverse childhood experiences is related to MDD during adult life; (2) the combination between MAO-A and MAO-B gene variants may ameliorate to a certain level the association of adverse childhood experiences [1] and depression; (3) adding interactive terms that are associated to higher correlations with the HDRS total score, implied a better model of depression severity; and (4) both genetic factors and temperamental traits could ameliorate the impact of adverse childhood experiences in the development of MDD in adulthood. This evidence concerns the gene MAOA and depressive symptom measurement.