Recent interest in frequent CNVs and their contribution to several common diseases led us to investigate relationships between frequent CNVs, brain volume variations and AUD. As seen in Table 3, the frequency of CNVs varies from 1% to 54%. Recent studies (Boyko et al., 2008; Conrad et al., 2010) suggest that common CNVs may not be able to account for unexplained heritability of complex traits left in SNP genome-wide association studies. However, these previous studies have restricted their threshold to be greater than 10% frequency. By decreasing our threshold to 1% the number of CNVs present in our analysis is increased and previously unexplored variations may be captured. In addition to this we suggest that the structural impact of frequent CNVs may depend upon the prevalence of the disease in question. Alcohol abuse and dependence remains highly prevalent and disabling in the United States, with lifetime alcohol dependence estimated at 12.5% (Hasin, Stinson, Ogburn, & Grant, 2007). Because AUD is a complex behavior we do not exclude the possibility of different types of variation (SNP and CNV) affecting the same
