(a) Voxel-wise genetic association analysis. This kind of analysis involves a genome-wide search at each voxel in the brain, after aligning all subjects’ images to a common template. (b) Extending this method to study brain connections, Jahanshad et al.30 described connectome-wide searches. They combined diffusion-based MRI tractography and cortical parcellations to perform GWAS at all connections between cortical regions of interest. Artificial Manhattan plots are illustrated here, with thresholds shown based on a single GWAS. Despite the vast number of tests, promising findings emerged, even after correction, from these whole-connectome genetic screens.