We also reported five overlapping DEGs shared between nicotine, anxiety and MDD phenotypes: SLC6A3, SPP1, NGFR, HDAC9 and IGF2. These genes were altered following nicotine exposure but also have a role in neurodevelopment, mood and anxiety disorders or closely interact with genes related to these phenotypes (Fan et al., 2020; Hobara et al., 2010; Lauterstein et al., 2016; Luo et al., 2015; Rafikova et al., 2021). This evidence concerns the gene SLC6A3 and major depressive disorder.