Interestingly, our partition-by-chromosome provided evidence for a greater proportional contribution to AD risk in AAs of common variants mapped to chromosome 4. Numerous known AD risk genes map to chromosome 4, most notably those that encode a set of alcohol dehydrogenase genes (e.g., [15]) and a set of GABA receptor subunits, most notably GABRA2 [5]. Although most published evidence obtains from European-ancestry populations (and Asian-ancestry populations for ADH1B [13]), several investigators have provided evidence directly relevant to African-ancestry populations as well [10,16]. This result, we believe, adds credence to the findings overall.
