For example, in a study analyzing 23 SNPs in ADRA2A as well as in a gene SLC6A2 (which encodes the norepinephrine transporter, NET1) in association with adult alcohol dependence identified two SNPs in ADRA2A associated with a positive family history of alcoholism and four SNPs in SLC6A2 associated with adult alcohol dependence (Clarke et al. 2010). Here, ADRA2A is linked to alcohol drinking.