Some single nucleotide polymorphisms (SNPs) have been identified that confer a susceptibility to specific aspects of alcohol dependence. The 1359G/A polymorphism (rs1049353) has been implicated in mediating the withdrawal severity experienced by chronic alcoholic patients where individuals homozygous for the A allele display more severe symptoms than other genotypes (Schmidt et al., 2002). However, the effect of this SNP on withdrawal severity is contested as another report failed to find evidence of 1359G/A’s association with the incidence of ethanol withdrawal seizures (Preuss et al., 2003). Furthermore, another study failed to find a correlation between rs1049353 and alcohol dependence, so it seems unlikely that this SNP is important for mediating a susceptibility to alcohol dependence (Zuo et al., 2007). However, the study by Zou et al (2007) did identify two SNPs (rs806371 and rs645467) conferring susceptibility and one SNP (rs806377) conferring resistance to alcohol dependence, but to date, no subsequent work has been published on these polymorphisms as regards alcohol dependence. In addition to these, another CNR1 SNP (rs202323) has been implicated in mediating cue-reactivity to alcohol in heavy drinkers, where
