... Caucasians [6]. In the present study, we applied PCR-RFLP in investigating the frequency of such SNPs in Vietnamese subjects as our preliminary assessment [7]. For OPRM1, the 118G allele appeared ... we extended our assessment by analyzing the frequencies of IVS2 +C691G locus in intron 2 of OPRM1 gene and G543A SNP in HRH2 gene in Vietnamese, using PCR-RFLP method. These results suggest ... a range of substance dependence and HRH2 is the gene coding histamine H2 receptor, the site of action for various compounds, e.g. amitriptiline and mianserin, used in the treatment of psychiatric...