receptor kinase 2 (GRK2) in a Ca2+-dependent manner [12]. Chronic cocaine exposure reduces the α-subunits of dopamine D2 receptor (D2R)-coupled Gi/o protein [21], Ca2+ influx {Hu, 2004 #155;Hu, 2004 #197} and activity of the adenylate cyclase calcineurin pathway in the nucleus accumbens medium spiny neurons (NAc MSN). Single nucleotide polymorphisms (SNPs) in genes encoding dopamine interacting proteins such as NCS-1 may alter the rewarding and reinforcing behavior following cocaine abuse. Therefore, NCS-1 is an interesting candidate gene for addiction risk susceptibility and the current study was designed with following aims (1) to investigate the genetic association between the NCS-1 gene and cocaine addicted individuals in AA and EA populations (2) to test the hypothesis that NCS-1 polymorphisms increase the risk for addiction in a sex specific manner.
