In contrast to our expectations in 2002, phenotyping has taken a backseat in this process. It became clear that having a precise or well-measured phenotype was far less relevant than having a huge sample. However, now that the field has a working strategy for gene discovery, the importance of phenotype is re-emerging. There is growing recognition that the genes you find are substantively affected by the phenotype you analyze. A salient example can be found in the substance use field, where GWAS for alcohol consumption and alcohol problems produced surprisingly different results, though they were both considered relevant phenotypes for understanding genetic contributions to alcohol use disorder (Mallard et al., 2021).
