Your DNA sequence is the same in every cell in your body, and is slightly different between any two individuals. Genetic differences can lead to changes in the size and structure of our brains, and risk for diseases. Despite that the DNA is identical in every cell in the body (with few exceptions), genetic variants can exert their effects only within specific cell types. In our paper, led by graduate student Nil Aygun, we mapped the effects of genetic variants on gene expression in two cell types of the developing cortex, neurons and progenitors, modeled with neural stem cells. We used our results to explain which genes and cell types influence brain structure. In the figure above, we found that a genetic variant affecting CENPW expression only in progenitors influences global cortical surface area. The results from this study can lead to a better understanding of how genetic variation leads to changes in our brains and risk for neuropsychiatric disorders.