Other linkage analyses of conduct disorder include analyses of DSM-III-R (American Psychiatric Association, 1987) and DSM-IV (American Psychiatric Association, 1994) conduct disorder criterion counts in a clinically ascertained sample of adolescent probands affected with substance abuse and delinquency and their siblings (249 proband-sibling pairs from 191 families genotyped on 374 markers; Stallings et al., 2005), and a linkage analysis of 733 sibling pairs in the Irish Affected Sib Pair Study of Alcohol Dependence (IASPSAD; genotyped on 1,020 markers; Kendler et al., 2006). In the clinically ascertained sample of adolescents, evidence of linkage (lod > 1.26) was found for regions on chromosomes 9, 3, and 17. In the IASPSAD, the strongest evidence for linkage (defined as lod > 2.0) was found for regions on chromosomes 1 and 14, with additional evidence for linkage on chromosome 2 (lod = 1.12) near the genomic region identified in the COGA study (Dick et al., 2004). Finally, in another linkage study of conduct disorder in a sample of 616 individuals from 18 families densely segregating highly comorbid ADHD and CD were genotyped on approximately 400
