We set out to explain this difference with further analysis. Because of the different nature of genetic experiments and molecular biology experiments, could they have discovered different genes in the same molecular network underlying addiction? We hypothesized that the genes identified by genetic studies and those by molecular biology studies may interact more frequently than expected by chance. Indeed, gene interaction enrichment analyses (See Details in Methods) revealed that genes identified by these two types of studies interact with each other more than expected by chance. The addiction susceptibility genes formed interactions with 37.2% (89/239) of the addiction-related genes identified by molecular biology studies that had known interaction data (Monte Carlo p-value < 0.0001). This result thus provides one explanation for the differences between the genes identified through genetics and those identified through molecular biologic and molecular pharmacologic approaches.
