It is important to attempt to disconfirm the present hypotheses regarding the higher-order genetic structure of child and adolescent psychopathology in future studies for at least three reasons. First, consistent with previous recommendations,6 this hypothesis implies that rather than searching for genetic polymorphisms associated with psychopathology one disorder at a time, it should be far more informative to simultaneously search for networks of pleiotropic genetic factors associated with multiple forms of psychopathology (and for the dimension-specific genetic and environmental factors uniquely associated with each dimension of psychopathology). This would require measuring multiple phenotypes in each study (across both internalizing and externalizing domains) and conducting genetic association analyses that squarely address the likelihood of widespread pleiotropy. Although the field will eventually discover which genetic variants are associated with multiple psychopathology dimensions even if we mostly study mental disorders one at a time, the present hypothesis imposes a testable model on the data that should make gene discovery more efficient and revealing about the biological nature of psychopathology.
