A novel tetra-primer ARMS-PCR for genotyping of the OPRM1 gene rs1799971 variant associated with opioid use disorders.

OBJECTIVES: A SNV is a single nucleotide change that can occur at any point in the genome. SNVs are the most common genetic variants that occur in the human genome, and a number of SNVs have been found to be associated with human traits and disease. Researchers genotype SNVs using TaqMan technology, DNA microarray, MALDI-TOF mass spectrometry, and automated sequencing, which are expensive and time-consuming. The OPRM1 gene rs1799971 (A118G) has been identified for its association with Opioid use disorder (OUD). The present study focused on developing a single step identification test using Tetra-Primer Amplification Refractory Mutation System-PCR (T-ARMS-PCR) to detect the presence of SNV OPRM1 rs1799971 (A118G). This study was performed to optimize the protocol for the designed four primers and validate it using a total of 52 buccal samples from volunteers who are currently under rehabilitation for the drug abuse disorder. RESULTS: Utilizing 52 DNA samples, a novel T-ARMS-PCR assay was successfully developed, tested, and validated. The products of the T-ARMS PCR for rs1799971 contained 395 bp as the control band, 186 bp as G allele (variant) and 257 bp as A allele (wild type), which were observed in the gel image. The genotype frequencies for the OPRM1 gene rs1799971 (A118G) were 44% (22/52) of homozygous variant type (GG), 28.9% (15/52) of homozygous wild type (AA) and 28.9% (15/22) of heterozygous (AG). The G allele frequency was 56.7% and A allele frequency was 43.3%.

Association between rs1799971 in the mu opioid receptor gene and methadone maintenance treatment response.

OBJECTIVE: Genetic variations can affect individual response to methadone maintenance treatment (MMT) for heroin addiction. The A118G variant (rs1799971) in the mu opioid receptor gene (OPRM1) is a potential candidate single nucleotide polymorphism (SNP) for personalized MMT. This study determined whether rs1799971 is related to MMT response or dose. METHODS: We recruited 286 MMT patients from a Han Chinese population. The rs1799971 genotype was determined via TaqMan genotyping assay. The genetic effect of this SNP on MMT response or dose was evaluated using logistic regression. A meta-analysis was performed to merge all available data to evaluate the role of rs1799971 in MMT using RevMan 5.3 software. RESULTS: No statistical significance was observed in the association between the OPRM1 rs1799971 and MMT response or dose in our Chinese cohort. Meta-analysis indicated that the OPRM1 A118G variation was not significantly associated with MMT response or dose requirement. CONCLUSION: The results suggest that rs1799971 in OPRM1 might not play a critical role alone in influencing MMT response or dose.

OPRM1 and CYP3A4 association with methadone dose in Iranian patients undergoing methadone maintenance therapy.

BACKGROUND: Investigations proposed that genetic polymorphisms within proteins in methadone pharmacokinetic and pharmacodynamics are critical factors in determination of methadone dose in methadone maintenance therapy (MMT). OBJECTIVE: This study aimed to assess the associations between two polymorphisms, CYP3A4 (rs2740574) and OPRM1 (rs1799971), with dose of methadone in Iranian patients undergoing MMT. METHODS: A total of 124 Iranian male subjects aged 18-65 years old who were confirmed to be addicted by the addiction diagnostic tests and underwent MMT were assessed. Patients were divided into three groups of low (less than 40 mg/day), moderate (more than 40 mg/day and less than 110 mg/day) and high (more than 110 mg/day) methadone dose consumption. DNAs of included patients were extracted from their blood samples and were assessed for CYP3A4 and OPRM1 polymorphisms. RESULTS: Results showed that there was no significant association between the studied polymorphisms and methadone dose in Iranian addicted patients underwent MMT (P > 0.05). CONCLUSIONS: CYP3A4 and OPRM1 single variations cannot explain variability in methadone dosage in MMT. Studying the interactions of more genetic factors in larger samples may elucidate factors influencing the required dose of methadone and better individualized therapy.

Significant association of mu-opioid receptor 1 haplotype with tobacco smoking in healthy control subjects but not in patients with schizophrenia and alcohol dependence.

Tobacco smoking is highly prevalent in patients with schizophrenia and alcohol dependence. The underlying neurobiology of nicotine addiction is complex. Rewarding effects of nicotine from cigarettes are associated, among others, with mu-opioid receptors encoded by the OPRM1 gene. The aim of the study was to evaluate the association between two OPRM1 gene polymorphisms, rs1799971 and rs510769, and tobacco smoking in Caucasian patients with schizophrenia, alcohol dependence, and healthy control subjects. The study included 1058 Caucasians (277 patients with schizophrenia, 359 patients with alcohol dependence, and 422 healthy control subjects), subdivided according to the nicotine dependence into smokers (i.e. current smokers) and non-smokers. A significant association was found between the GC haplotype (OPRM1 rs1799971 and rs510769) and smoking in healthy controls, but not in patients with schizophrenia and alcohol dependence. A nominal association was detected in all cases/controls, but this significance did not survive the correction for the multiple testing. This is the first study to reveal that nicotine dependence is associated with the GC haplotype of the OPRM1 rs1799971 and rs510769 in all subjects or specifically in healthy controls. These results did not confirm the strong connection between OPRM1 polymorphisms and nicotine dependence in schizophrenia or alcohol dependence.

The association between the OPRM1 A118G polymorphism and addiction in a Turkish population.

Susceptibility to addiction has a complex genetic basis that includes genes associated with the action and metabolism of drugs of abuse. One important gene in that respect is OPRM1, which codes for the µ-opioid receptor and has an important role in mediating the rewarding effects of addiction substances. The aim of our study was to assess the prevalence of the OPRM1 A118G polymorphism (rs1799971) in Turkish population and to investigate its association with opioid and other substance addiction. In addition, we examined the association of rs1799971 in addicted patients who were also diagnosed with psychiatric disorders. The study included 103 patients addicted to opioids, cocaine, ecstasy, alcohol, lysergic acid diethylamide (LSD), cannabis, and sedative/hypnotic substances and 83 healthy volunteers with similar demographic features as controls. rs1799971 polymorphisms were identified with the polymerase chain reaction restriction fragment length polymorphism method (PCR-RFLP). The genotype frequencies were significantly higher in the addicted patients than controls (32.0 % vs 16.9 %, respectively; p=0.027). The prevalence of the G allele was 16.1 % in the addicted group and 8.4 % in the control group (p=0.031). Our study confirmed the association between the rs1799971(G) allele frequency and opioid and other substance addiction, but not with psychiatric disorders.

Binge-Like Eating Is Not Influenced by the Murine Model of OPRM1 A118G Polymorphism.

Impairments in opioid receptor signaling have been implicated in disordered eating. A functional variant of the OPRM1 gene is a guanine (G) substitution for adenine (A) at the 118 position of exon 1 (A118G). The influence of the A118G variant on binge eating behaviors and the effectiveness of pharmacotherapies used to treat binge eating have not been characterized. Mice were generated with A to G substitution at the 112 position on exon 1 to produce a murine equivalent of the human A118G variant. Homozygous female mice (AA or GG) were exposed to intermittent access to a highly palatable sweet-fat food with or without prior calorie deprivation to promote dietary-induced binge eating. There were no genotype-dependent differences in the dietary-induced binge eating. However, GG mice exposed to intermittent calorie restriction (Restrict) had higher body weights compared with GG mice exposed to intermittent sweet fat-food (Binge) and ad libitum feeding (Naive). Acute oral dosing of lisdexamfetamine (0.15, 0.5, and 1.5 mg/kg) or sibutramine (0.3, 1, and 3 mg/kg) did not produce genotype-dependent differences in binge-like eating. In addition, no genotype-dependent differences in binge-like eating were observed with chronic (14-day) dosing of lisdexamfetamine (1.5 mg/kg/day) or sibutramine (3 mg/kg/day). In the chronic dosing, body weights were higher in the GG Restrict compared with AA Restrict. Our findings suggest that the A112G polymorphism does not influence binge eating behaviors or pharmacotherapies for treating binge eating.

Opioid receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) and postoperative nausea and vomiting.

BACKGROUND: OPRM1-A118G polymorphism (A > G, rs1799971) is associated with interindividual variability in both response to postoperative pain and opioid treatment. The aim of this meta-analysis is to identify the predictive strength in the current literature of OPRM1-A118G polymorphism to postoperative anesthetic reactions, including nausea, vomiting, pruritus and dizziness. METHODS: PubMed, EMBASE, Cochrane Library, Web of Knowledge, Google Scholar and CNKI database were searched to find gene-association researches exploring the impacts of OPRM1-A118G polymorphism on postoperative side effects (time: up to July 2016). Odd ratios (ORs) with 95% confidence intervals (95% CIs) were estimated in allele model, homozygote model, heterozygote model, dominant model and recessive model. Sensitivity analysis and potential bias were also assessed. RESULTS: 137 articles were retrieved from databases. 17 eligible studies, including 4690 patients were considered in the meta-analysis. The ORs with 95% CIs of postoperative nausea, vomiting, nausea and vomiting (PONV), pruritus and dizziness in the five genetic models mentioned above were determined. Postoperative vomiting was significantly associated with OPRM1-A118G polymorphism in homozygote (OR: 0.422; 95% CI: 0.254, 0.701; P = 0.001), dominant (OR: 0.765; 95% CI: 0.592, 0.987; P = 0.040) and recessive (OR: 0.439; 95% CI: 0.268, 0.717; P = 0.001) models. The 118G allele was associated with a reduced risk of vomiting. No other associations were detected. There was no evidence of publication bias. CONCLUSIONS: OPRM1-A118G polymorphism (A > G) is associated with a reduced risk of postoperative vomiting, but not nausea, pruritus and dizziness. The results should be interpreted with caution due to limited sample and possible heterogeneity between the included studies. Well-designed and large-scale studies are necessary to confirm our results.

The frequency of DRD2 rs1076560 and OPRM1 rs1799971 in substance use disorder patients from the United Arab Emirates.

BACKGROUND: Dopaminergic and opioid systems are involved in mediating drug reward and reinforcement of various types of substances including psychoactive compounds. Genes of both systems have been candidate for investigation for associations with substance use disorder (SUD) in various populations. This study is the first study to determine the allele frequency and the genetic association of the DRD2 rs1076560 SNP and OPRM1 rs1799971 SNP variants in clinically diagnosed patients with SUD from the United Arab Emirates (UAE). METHODS: A cross-sectional case-control cohort that consisted of 512 male subjects was studied. Two hundred and fifty patients with SUD receiving treatment at the UAE National Rehabilitation Center were compared to 262 controls with no prior history of mental health and SUD. DNA from each subject was extracted and genotyped using the TaqMan ® SNP genotyping assay. RESULTS: There were no significant associations observed for DRD2 rs1076560 SNP, OPRM1 rs1799971 SNP, and combined genotypes of both SNPs in the SUD group. CONCLUSION: Further research is required with refinements to the criteria of the clinical phenotypes. Genetic studies have to be expanded to include other variants of the gene, the interaction with other genes, and possible epigenetic relationships.

Association of opioid receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) with nicotine dependence.

BACKGROUND AND OBJECT: Whether opioid-receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) is associated with nicotine dependence is controversial. We analyzed the combined results from published studies of this possibility. METHODS: Literature reviews were performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Web of Science, Chinese National Science Infrastructure (CNKI), PubMed, Embase and Google Scholar database searches using MeSH terms were conducted to find all relevant researches up to October 2016. Odds ratios (ORs) and their 95% confidence intervals (95% CIs) were calculated in allele, homozygote, heterozygote, dominant and recessive models. Ethnicity-specific subgroup meta-analysis, heterogeneity, sensitivity analysis and publication bias were considered. RESULTS: Seven eligible studies with 3313 patients were included. The ORs in the five genetic models mentioned above were 1.000 (95% CI: 0.906, 1.104; p = 0.999), 1.032 (95% CI: 0.771, 1.381; p = 0.834), 0.963 (95% CI: 0.799, 1.162; p = 0.696), 1.006 (95% CI: 0.916, 1.104; p = 0.907), 0.967 (95% CI: 0.715, 1.309; p = 0.830), respectively. Only in dominant model is the association significant. Upon ethnicity-specific subgroup analysis, there is no statistical significance. CONCLUSION: OPRM1-A118G polymorphism (A>G) is not associated with nicotine dependence.

Lack of associations of the opioid receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) with alcohol dependence: review and meta-analysis of retrospective controlled studies.

BACKGROUND: Studies have sought associations of the opioid receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) with alcohol-dependence, but findings are inconsistent. We summarize the information as to associations of rs1799971 (A > G) and the alcohol-dependence. METHODS: Systematically, we reviewed related literatures using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Embase, PubMed, Web of Knowledge, and Chinese National Knowledge Infrastructure (CNKI) databases were searched using select medical subject heading (MeSH) terms to identify all researches focusing on the present topic up to September 2016. Odds ratios (ORs) along with the 95% confidence interval (95% CI) were estimated in allele model, homozygote model, heterozygote model, dominant model and recessive model. Ethnicity-specific subgroup-analysis, sensitivity analysis, heterogeneity description, and publication-bias assessment were also analyzed. RESULTS: There were 17 studies, including 9613 patients in the present meta-analysis. The ORs in the 5 genetic-models were 1.037 (95% CI: 0.890, 1.210; p = 0.64), 1.074 (95% CI: 0.831, 1.387; p = 0.586), 1.155 (95% CI: 0.935, 1.427; p = 0.181), 1.261 (95% CI: 1.008, 1.578; p = 0.042), 0.968 (95% CI: 0.758, 1.236; p = 0.793), respectively. An association is significant in the dominant model, but there is no statistical significance upon ethnicity-specific subgroup analysis. CONCLUSION: The rs1799971 (A > G) is not strongly associated with alcohol-dependence. However, there are study heterogeneities and limited sample sizes.

The µ-opioid receptor nonsynonymous variant 118A>G is associated with prolonged abstinence from heroin without agonist treatment.

AIM: This study assesses whether opioid-related gene variants contribute to reduced vulnerability to relapse to heroin in persons who are not treated with µ-opioid receptor agonist. METHODS: Genotypes of 71 SNPs, in nine genes, were analyzed for association with long-term abstinence in former heroin-dependents of European/Middle Eastern ancestry, either without agonist treatment (n = 129) or in methadone maintenance treatment (n = 922). RESULTS: The functional OPRM1 nonsynonymous SNP rs1799971 (118A>G) showed significant association with long-term abstinence (Ppermutation  = 0.03, dominant model, OR: 2.2; 95% CI: 1.5-3.3). CONCLUSION: Since the stress axis is regulated in part by ß-endorphin, this functional OPRM1 SNP may blunt the endogenous stress response and contribute to reduced vulnerability for relapse.

A prospective study of genetic factors, human laboratory phenotypes, and heavy drinking in late adolescence.

Subjective responses to alcohol are considered candidate endophenotypes for alcohol use disorder and appear to anticipate future consumption. However, prospective studies have been rare, and laboratory research has typically examined subjective responses absent measures of self-administration. This study examined the association of subjective responses with subsequent laboratory self-administration, also evaluating laboratory phenotypes in relation to putative genetic risk factors [family history (FH) of alcohol dependence and OPRM1 genotype] and subsequent heavy drinking. Participants (N = 61, M = 19.89 years, SD = 0.86) completed laboratory sessions involving intravenous alcohol challenge (Session 1) and free-access intravenous self-administration (Session 2), followed by prospective assessments. Multilevel modeling showed that higher reported stimulation and lower sedation during Session 1 independently predicted greater alcohol self-administration during Session 2. Although self-administration did not differ by FH group, participants with the OPRM1 118G allele evidenced steeper breath alcohol concentration (BrAC) trajectories and greater peak BrAC relative to 118A homozygous participants. Prospective analyses supported significant indirect associations between Session 1 subjective responses and 6-month heavy drinking via peak BrAC in Session 2. Additionally, significant indirect associations of FH (via Session 1 stimulation and Session 2 peak BrAC) and OPRM1 (via peak BrAC) with follow-up heavy drinking were observed. These results further support the utility of human laboratory phenotypes in prospective studies of alcohol use disorder risk and highlight the potential role of self-administration phenotypes in longitudinal research.

Associations of OPRM1 A118G and alcohol sensitivity with intravenous alcohol self-administration in young adults.

Human laboratory and animal models implicate variation in the µ-opioid receptor gene (OPRM1) as relevant for alcohol-related reward. OPRM1 is associated with alcohol self-administration in non-human primate studies, but the relevance of this finding to human models is unclear. This study used computer-assisted self-infusion of ethanol (CASE) to examine associations among OPRM1 A118G genotype, subjective responses to alcohol and intravenous alcohol self-administration in young heavy drinkers (n = 40, mean age = 19.95 years, SD = 0.82). Participants completed a 2-hour CASE session comprising a priming phase followed by ad libitum self-administration in a free-access paradigm. Participants achieved a mean peak breath alcohol concentration (BrAC) of 81.18 mg% (SD = 24.96). Those with the OPRM1 118G variant (GA or GG genotypes) achieved significantly higher peak BrAC (M = 94.90 mg%, SD = 16.56) than those with the AA genotype (M = 74.46 mg%, SD = 25.36), reflecting a significantly greater number of alcohol requests among GA/GG participants. Eighty percent of GA/GG participants surpassed a threshold defining a laboratory analog of heavy alcohol exposure (80 mg%) compared with 46 percent of AA participants. Results indicated significant associations between subjective measures of alcohol sensitivity and CASE outcomes, although the pattern of findings differed across self-report measures. Subjective responses did not differ by OPRM1 status. These results offer further support for the feasibility of the CASE paradigm and provide initial evidence for an association of OPRM1 with alcohol self-administration in a human laboratory context.

Mu opioid receptor polymorphism, early social adversity, and social traits.

A polymorphism in the mu opioid receptor gene OPRM1 (rs1799971) has been investigated for its role in sensitivity to social contexts. Evidence suggests that the G allele of this polymorphism is associated with higher levels of sensitivity. This study tested for main effects of the polymorphism and its interaction with a self-report measure of childhood adversity as an index of negative environment. Outcomes were several personality measures relevant to social connection. Significant interactions were obtained, such that the negative impact of childhood adversity on personality was greater among G carriers than among A homozygotes on measures of agreeableness, interdependence, anger proneness, hostility, authentic pride, life engagement, and an index of (mostly negative) feelings coloring one's world view. Findings support the role of OPRM1 in sensitivity to negative environments. Limitations are noted, including the lack of a measure of advantageous social environment to assess sensitivity to positive social contexts.