The first linkage analysis of conduct disorder diagnoses came from the Collaborative Study on the Genetics of Alcoholism (COGA; Begleiter et al., 1995; Dick et al., 2004). In total, 2282 participants from 262 families densely affected with alcoholism were genotyped on 336 markers that were 10.5 cM apart, on average. Nonparametric linkage analysis identified regions of interest (defined in this study as lod ≥ 1.5) on chromosomes 2, 3, 12, and 19. The region identified on chromosome 2 was also identified in linkage studies of alcohol dependence and suicidality in the same sample (Foroud et al., 2000; Hesselbrock et al., 2004) and suicidality in other samples (Willour et al., 2007; Zubenko et al., 2004), which is notable in view of the genetic correlation between conduct disorder and other disorders characterized by disinhibition (Kendler et al., 2003; Krueger et al., 2002; Slutske et al., 1998; Young et al., 2000).
