Empirical subtyping methods are based on theories that emphasize the multifaceted nature of substance dependence and related behaviors [Basu et al., 2004]. Multivariate cluster analysis has been used commonly to subtype substance dependence [Cardoso et al., 2006; Gelernter et al., 2006; Kuo et al., 2008; Chan et al., 2011], including CD [Kranzler et al., 2008]. However, these approaches have focused exclusively on the cluster homogeneity of the clinical features, rather than aiming to optimize the heritability of the subtypes and enhance the potential to identify specific genes that contribute to subgroup membership.
