Results of our analysis suggest that most exons of the OPRM1 gene annotated in the mouse also exist in primates (Fig. 1A). Our results also predict new exon–intron boundaries (see Fig. 1B for exon 13 example), an alternative transcription start site and conserved promoter (43,44) upstream from the predicted primate exon 11 with conserved putative transcription factor binding sites in primates and rodents (Supplementary Material, Fig. S1). These data support the existence of a larger and more complex human OPRM1 gene (Fig. 1).
