Although some studies have used HWE tests to detect genotyping errors, recent research has put forth strong arguments against this practice (Leal, 2005; Zou and Donner, 2006). Additionally, behavioral geneticists have noted that tests for HWE assume that genotypes are at random sample from the general population whereas many behavioral genetic studies ascertain individuals through their disease status, or as is the case in this study, through drinking patterns. As a result, when a marker is associated with a given phenotype, the corresponding genotype may no longer be a random sample, in which case even if the marker is in HWE with the population, departures from HWE may be noted in a selected sample (Li and Li, 2008). In other words, deviations from HWE are thought to be most likely at trait susceptibility loci or polymorphisms that are in LD with the susceptibility locus (Leal, 2005). The departure from HWE observed in this sample may be the result of a selected sample of heavy drinkers, selection pressure as demonstrated by Enoch and colleagues (2009), other unknown factors, or a combination thereof.
