Genome-wide association studies (GWAS) adopt an agnostic approach to examine the entire genome for association with a phenotype in large samples (Visscher et al. 2017). Large sample sizes are needed for GWAS because of the polygenicity of complex traits and the low effect size of each individual single nucleotide polymorphism (SNP). Few studies have the data required to model developmental considerations in GWAS, instead relying on phenotype definitions that pool across time and developmental periods to maximize the number of samples that can be included in a single meta-analysis. This approach may not accurately model the ways that genetic influences on complex psychiatric and behavioral phenotypes vary across development.
