Lack of representation of individuals of African descent in gene identification studies is problematic for reasons additional to the problems caused by under-representation of AAs in twin research. Since human populations originated in Africa, the genetic architecture of African populations is characterized by greater levels of genetic diversity than European populations.40,41 Further, African populations are characterized by differences in allele frequencies and linkage disequilibrium (LD) patterns as compared to other non- African populations.41–43 These factors contribute to the challenge of translating genetic findings from populations of European ancestry populations to populations of African descent. In particular, the greater genetic diversity in populations of African descent makes it more likely that there may be causal variants present in populations of African descent that would not be detected in populations of European descent. Differences in allele frequencies between populations mean that effects detected in populations of European descent will not necessarily have the same impact in populations of African descent. For example, if the causal variant is less common in populations of African descent, it may play less of a role in
