Gene identification efforts for conduct disorder are in their infancy. Although the linkage and association studies have identified a number of suggestive signals, the inconsistencies across the studies are noticeable. This reflects the inherent difficulties in identifying replicable genes and genetic variants associated with complex psychiatric and behavioral outcomes. There are many potential reasons for this difficulty, including small effect sizes, rigorous corrections for multiple testing of thousands and millions of genetic variants, and genetic heterogeneity. Furthermore, the sample sizes for the conduct disorder GWAS summarized here are relatively small compared to other areas of psychiatric and complex traits genetics, which impacts the power to detect small effects. The large sample sizes needed for gene identification efforts for psychiatric traits is illustrated most clearly in the area of schizophrenia research, where the most recent mega-analysis of 36,989 schizophrenia cases and 113,075 controls identified association with 108 loci (Schizophrenia Working Group of the Psychiatric Genomics, 2014).
