In this paper we aim to analyze the effect of two Single Nucleotide Polymorphisms (SNPs) from the opioidergic system on TESI and TWOSI: SNP rs1799971 (A118G) from the first exon of the gene OPRM1 and rs105660 (36 G > T) from the gene OPRK1. The G allele of rs1799971 results on an amino acid change (N40D) that decreases MOR expression and has been associated with an increased sensitivity to social rejection, a higher risk to develop major depressive episode (MDE) after an adverse life event and completed suicide42,43. Here, OPRM1 is linked to major depressive episode.