significant, differences in genetic influences underlying the two sets of criteria, though the total heritability is almost unchanged. There is no indication that this represents an improvement in the validity of the diagnosis. A study examining prognosis of the individuals in D4-only and D5-only could provide insight as to whether one group experiences a more negative outcome than the other, and could thus be considered more deserving of a diagnosis, but such data are not available for this sample. In light of these analyses, we would assert that the proposed changes do not represent an unequivocal improvement in diagnostic validity.
