In contrast, there were no significant findings for heritability or shared genetic effects in AA individuals. This should not be taken as evidence that genetic effects in AA individuals differ from those in EA individuals. Rather, this report highlights an interpretational disparity between EA and AA individuals. There are no twin studies conducted in primarily non-EA populations, and hence there is no prior information indicating whether heritability might differ across ancestry groups. Second, polygenic methods like PRS and LDSC rely on external data resources that are far less common generally, and nonexistent for many, non-EA populations. Third, newer methods, such as LDSC, have not been adapted for recently admixed genomes, and thus they cannot be applied to AA and many LA individuals. Other factors responsible for lower power in the AA PTSD analysis are Eurocentric bias on genotyping arrays and the inherently greater genetic variation in the African portions of AA individuals’ chromosomes, necessitating more markers to achieve the same proportion of genomic coverage. Given these factors, publication of this relatively large sample of AA individuals is particularly important.
