YKT6 and attention deficit-hyperactivity disorder: Besides, Cplx2, Ykt6, and Cplx3 whose products participate in the SNARE complex were specifically upregulated by smoking but not by nicotine exposure, which could have relevant neurocognitive and behavioral implications, in support of the observed relationship between deficits in the SNARE protein SNAP-25 and maternal smoking with Attention Deficit Hyperactivity Disorder (ADHD) (33,55,56).