A census of cells in time: quantitative genetics meets developmental biology

► eQTL analysis is a means to study the genetic basis of transcriptional hierarchies. ► Transcriptional regulation will change depending on developmental context. ► New, high-throughput methods to isolate specific cell types are being developed. ► Phenotypes, including gene expression, should be sampled across developmental time. ► Combining eQTL analysis with developmental principles promises unprecedented insights.