Comorbid psychopathy is not associated with increased D2 dopamine receptor TaqI A or B gene marker frequencies in incarcerated substance abusers.

Substance ~buse and antisocial personality diagnoses such as psychopathy or antisocial personality disorder (ASP) each exhibit genetic underpinnings and share prominent comorbidity (Devor and Cloninger 1989; Crowe 1974; Schulsinger 1977; Smith and Newraan 1990). Thus, shared underlying genetic factors may contribute to ~he pathogenesis of both disorders (e.g., Gorenstein and Newman 1980). Lhlkage and association analyses can help to asse~s whether a specific gene for one disorder can independently or addifively contribute to vulnerability to another (Baron et al, 1990). The genetic ma-kers most strongly implicated in vulnerability to substance abuse are the AI and BI TaqI restriction fragment length polymorphizms (~VLPs) at the 3' and 5' ends of the dopamine D2 receptor (DRD2) gene (Blum et al 1990; Cloning~r 1991; Uhl et al 1992, 1993). Seven studies have compared TaqI AI marker frequencies in substance abusers and controls assessed to exclude substance abuse (Amadeo et al 1992; Blum et al 1990, 1991; Comings et al 1991; Cook et al 1992; Parsian et al 1991; Smith et al 1992). Combined data from these seven studies reveals that 42.3% (254/600) of substance, abusers and 19.4% (38/196) of assessed controls displayed the AI marker (Table 1). Only two studies have ex~,n.i..,w.d the B ! marker i~ substance abusers and assessed controls (Blum et al 1993; Smith et al 1992). Of substance abusers 32.8% (1041317) and of controls 14.0% (12/86) displayed the BI marker (Table 2). Other studies utilizing controls unassessed to exclude substance abuse have failed to find an association between the DRD2 gene and substance abuse (Bolos et al 1 9 ~ , G~,~t,,,~, ¢t al i991; lurner ut al 1992).