One key piece of basic biological information that is missing is knowledge of cell type diversity and its molecular basis in the brain. To fully interpret the mechanisms of genetic variants it is necessary to have a more complete molecular and cellular parts list of the developing and mature brain. Moreover, as most common variants lie in presumptive regulatory regions, we need to integrate emerging knowledge about cells and circuits with an unbiased understanding of mechanisms of gene regulation across neurodevelopmental stages. All of these goals will be hastened by organized efforts such as the Brain Initiative (braininitiative.nih.gov/), the Allen Institute (http://alleninstitute.org), psychEncode (http://psychencode.org), Genotype-Tissue Expression (www.gtexportal.org), and the PGC.
