Genome-wide association studies (GWAS) have been successful at identifying risk genes for complex traits, but largely unsuccessful in identifying major risk loci. One contributing factor is the reliance on diagnosis – a dichotomous phenotype – rather than continuous phenotypes, which have greater statistical power and may be better correlated with the underlying genetic risk. Furthermore, GWAS have been conducted almost exclusively in samples of European ancestry, which risks missing variants at very low frequency in European populations. We address these two issues in the present study by considering additional phenotypes related to AD risk – flushing response and the maximum number of standardized drinks consumed in a 24-hour period – in a Chinese population underrepresented in GWAS. Flushing response (and the associated negative physical symptoms that occur in the presence of high acetaldehyde concentrations) is an intermediate phenotype that appears to mediate the volume of alcohol an individual can consume comfortably. Because this phenotype is most common in East Asian populations, occurring in nearly 40% of individuals in the present study but less than 10% of Europeans (Whitfield and Martin
