Because KAT2B is a novel genetic susceptibility factor for drug abuse, we built a GeneMANIA (Zuberi et al., 2013) network centered around KAT2B to find related genes that may have functional links to drug abuse. Figure 3 shows that 20 genes were implicated in the KAT2B network, based on their co-expression, physical interactions, predicted functional relationships (e.g., protein interactions), and pathway data. We investigated rs9829896 as a trans- eQTL for transcripts encoded by the 20 genes identified in the KAT2B network via GeneMANIA. Two gene transcripts were associated with rs9829896 at P<0.05: the C allele being associated with lower expression of MAML1 (P=0.043) and CREBBP (P=0.011) in AAs only. MAML1 functions as a transcriptional co-activator of the Notch signaling pathway that is involved in cell fate determination (Wu et al., 2000). Notch signaling has been indicated for altering drug reward properties in Drosophila melanogaster (Kaun et al., 2011), but the function of MAML1 in relation to drug abuse is unclear. In contrast, CREB binding protein (CREBBP) is a member of the cyclic adenosine monophosphate (cAMP) pathway that has been widely
