The importance of considering sex in human genetic studies is not just limited to the realm of uncovering high-confidence associations between genotype and phenotype that would be hidden when sex is not considered. Ignoring potential sex-specific association both stalls scientific progress and can have even broader consequences. For example, we know that in vivo pharmacodynamics and pharmacokinetics can depend on sex (e.g., [27–29]), ethnicity (e.g., [30]), and genotype, but human geneticists often assess the impact of ethnicity and not sex. Important theoretical (e.g., population migration, natural selection, founder effect, etc.) and historical (e.g., subtle differences in ethnicity between case and control populations led to false positive findings) reasons underscore why geneticists assess the impact of ethnicity, but there are clear theoretical and evidence-based justifications for why assessing biological sex is important as well, as discussed above.
