Rs1344706 may also influence structure of addiction-relevant brain regions. In reporting the rs1344706 association with heroin addiction, Sun et al. (in press) showed that its risk allele and haplotype were associated with greater gray matter volume across several human brain regions; they detected an interaction with heroin addiction specifically in the left sensorimotor cortex, a region that is relevant for developing and preserving addiction, whereby the risk haplotype was associated with greater gray matter volume in heroin abusers but lower grey matter volume in controls. This association involving rs1344706 and grey matter by disease state is consistent with prior findings in healthy individuals (Voineskos et al., 2011) and schizophrenia cases and controls (Nenadic et al., 2015). These studies further linked rs1344706-A to reduced cognitive function (Sun et al., in press, Voineskos et al., 2011).
