The association studies cited above were carried out in European-descent samples. Studying this region in individuals of African descent provides an opportunity to confirm its role in an important and understudied population. Also, the contrasting genetic architecture in Africans and Europeans can be leveraged to narrow down the potential functional source of the disease associations [24]. In the European ancestry population, many highly correlated SNPs often can detect the same association signal, and determining which variant(s) are “causal” is not straightforward. LD and allele frequencies can differ between European and African populations. For instance, in HapMap, rs16969968 is non-polymorphic in the YRI (Yoruba in Ibadan, Nigeria) sample; for rs3743078, the minor allele in YRI (“C”, 33%) is the major allele (77%) in CEU (CEPH, Utah residents with ancestry from northern and western Europe) [25].
