The dopamine D2 receptor gene : a genetic risk factor in substance abuse

FRANÇAIS :
On étudie la prévalence du variant génétique Taq1 du gène DRD2 codant pour la dopamine. Une augmentation de 21 % de la prévalence du D2A1 est relevée chez les sujets alcooliques, de 32 % chez ceux qui en sont réellement dépendants et de 42 % chez ceux qui dépendent d'alcool et de drogues. Chez les toxicomanes lourds, dépendants d'une ou plusieurs substances, 56,9 % portent l'alléle D2A1 contre 28,2 % de ceux qui ne consomment qu'une substance. Les analyses statistiques montrent que les porteurs de D2A1, comparés aux porteurs D2A2A2 sont plus impliqués dans la criminalité. L'alléle D2A1 serait associé significativement à la toxicomanie et aux comportements agressifs.
ENGLISH :
To examine the possible role of genetic variants of dopamine D2 (DRD2) gene in susceptibility to drug abuse we determined the prevalence of the TaqI A1 variant of the DRD2 gene in 200 white patients. While the prevalence of the D2A1 allele was not significantly increased over controls, it did increase from 21 % in subjects with alcohol abuse only to 32 % in subjects with alcohol dependence only, consistent with other studies showing an association with the severity of alcoholism. Of those who spent more than $25/week on two or more substances, 56,6 % carried the D2A1 allele versus 28,2 % of those abusing a single substance. Multiple logistic regression analysis showed a highly significant association between multiple substance abuse based on money spent and the presence of the D2A1 allele and age of onset of abuse. D2A1 carriers exceeded D2A2A2 subjects for a history of being expelled from school for fighting, and of those ever jailed for violent crimes. We concluded that possession of the D2A1 allele is significantly associated with drug abuse/dependence and some aggressive behaviors.