OPRD1 gene affects disease vulnerability and environmental stress in patients with heroin dependence in Han Chinese

The role of personality traits and life stress in alcohol use disorder: Insights from NGF gene polymorphisms of Han Chinese population in Taiwan

OBJECTIVE

Alcohol use disorder (AUD) is a complex neuropsychiatric condition influenced by genetic and environmental factors. Nerve growth factor (NGF) plays a crucial role in neuronal neuroplasticity and chronic alcohol consumption may alter NGF levels in specific brain regions. The study investigates the associations between NGF gene polymorphisms, susceptibility to AUD, and specific stress and personality characteristics.

METHODS

Our study involved 1133 participants from a homogeneous Han Chinese population, 587 of whom had AUD and 546 were controls. To minimize potential confounding factors, the AUD group was stratified by sex and age at baseline. A total of 414 participants completed the Life Event Questionnaires (LEQ), while 559 participants completed the Tridimensional Personality Questionnaire (TPQ).

RESULTS

The NGF's rs7523654 and rs11102929 loci were significantly associated with AUD, especially in female subgroups. Additional haplotype research confirmed similar findings. AUD patients showed more vital propensities for novelty seeking (NS) and harm avoidance (HA) compared to controls. Additionally, they recorded higher negative LEQ results. Notably, HA and negative LEQ scores among AUD people were significantly affected by the SNP rs11102929 in the NGF gene. The age at which AUD first manifested and NS scores showed a reverse link, suggesting that a higher NS characteristic may predispose people to develop AUD earlier in life.

CONCLUSION

The findings suggest that the NGF gene may influence AUD susceptibility and its links to personality traits and life stress. However, the small sample of women with AUD limits the reliability of these associations, highlighting the need for further study.

Genetic Associations of Persistent Opioid Use After Surgery Point to OPRM1 but Not Other Opioid-Related Loci as the Main Driver of Opioid Use Disorder

Persistent opioid use after surgery is a common morbidity outcome associated with subsequent opioid use disorder, overdose, and death. While phenotypic associations have been described, genetic associations remain unidentified. Here, we conducted the largest genetic study of persistent opioid use after surgery, comprising ~40,000 non-Hispanic, European-ancestry Michigan Genomics Initiative participants (3198 cases and 36,321 surgically exposed controls). Our study primarily focused on the reproducibility and reliability of 72 genetic studies of opioid use disorder phenotypes. Nominal associations (p < 0.05) occurred at 12 of 80 unique (r2 < 0.8) signals from these studies. Six occurred in OPRM1 (most significant: rs79704991-T, OR = 1.17, p = 8.7 × 10-5), with two surviving multiple testing correction. Other associations were rs640561-LRRIQ3 (p = 0.015), rs4680-COMT (p = 0.016), rs9478495 (p = 0.017, intergenic), rs10886472-GRK5 (p = 0.028), rs9291211-SLC30A9/BEND4 (p = 0.043), and rs112068658-KCNN1 (p = 0.048). Two highly referenced genes, OPRD1 and DRD2/ANKK1, had no signals in MGI. Associations at previously identified OPRM1 variants suggest common biology between persistent opioid use and opioid use disorder, further demonstrating connections between opioid dependence and addiction phenotypes. Lack of significant associations at other variants challenges previous studies' reliability.

Association of OPRD1 Gene Variants with Changes in Body Weight and Psychometric Indicators in Patients with Eating Disorders

Objectives: This study aimed to investigate whether genetic variations in the OPRD1 gene affect psychopathological symptoms and personality dimensions in eating disorders (ED) patients and/or contribute to ED risk. Methods: The study involved 221 female patients with anorexia nervosa (AN), 88 with bulimia nervosa (BN), and 396 controls. Sixteen tag-single nucleotide polymorphisms (SNPs) in OPRD1 were identified. Psychometric evaluations were conducted using the Symptom Checklist 90 Revised (SCL-90R) and the Eating Disorders Inventory Test-2 (EDI-2). p-values obtained by regression models were corrected for multiple testing by the False Discovery Rate (FDR) method. Results: In AN patients, genotypes rs204077TT and rs169450TT were linked to lower body-mass index (BMI) values (FDR-q = 0.035 and 0.017, respectively), as was rs2234918 in a log-additive model (BMI: 18.0 ± 0.28, 17.22 ± 0.18 and 16.59 ± 0.39 for TT, TC and CC carriers, FDR-q = 0.012). Additionally, AN patients carrying the rs72665504AA genotype had higher scores in interpersonal distrust (FDR-q = 0.030), whilst BN carriers of rs513269TT and rs2873795TT showed lower scores in ineffectiveness (FDR-q = 0.041 and FDR-q = 0.021). In the AN group, BMI correlated with variability in a distal haplotype (rs508448/rs204077/rs223491, FDR-q = 0.028), which was also associated with the global positive symptom total (PST) index of SCL-90R (FDR-q = 0.048). Associations were more noticeable in BN patients; again, the distal region of the gene was linked to EDI-2 total scores (FDR-q = 0.004-0.048 for the four last haplotypes) and two global SCL-90R indices (GSI: FDR-q = 0.011 and positive symptom distress index (PSDI): FDR-q = 0.003 for the last s204077/rs2234918/rs169450 combination). No associations with ED risk were observed. Conclusions: Genetic variation in the OPRD1 gene, particularly in its distal region, is associated with BMI and psychopathological comorbidities in ED patients.

A systems omics-based approach to decode substance use disorders and neuroadaptations

Substance use disorders (SUDs) are a group of neuropsychiatric conditions manifesting due to excessive dependence on potential drugs of abuse such as psychostimulants, opioids including prescription opioids, alcohol, inhalants, etc. Experimental studies have generated enormous data in the area of SUDs, but outcomes from such data have remained largely fragmented. In this review, we attempt to coalesce these data points providing an important first step towards our understanding of the etiology of SUDs. We propose and describe a 'core addictome' pathway that behaves central to all SUDs. Besides, we also have made some notable observations paving way for several hypotheses; MECP2 behaves as a master switch during substance use; five distinct gene clusters were identified based on respective substance addiction; a central cluster of genes serves as a hub of the addiction pathway connecting all other substance addiction clusters. In addition to describing these findings, we have emphasized the importance of some candidate genes that are of substantial interest for further investigation and serve as high-value targets for translational efforts.

OPRD1 SNPs associated with opioid addiction are cis-eQTLs for the phosphatase and actin regulator 4 gene, PHACTR4, a mediator of cytoskeletal dynamics

Several OPRD1 intronic variants were associated with opioid addiction (OD) in a population-specific manner. This follow-up study aims to further characterize the OPRD1 haplotype pattern of the risk variants in different populations and apply in silico analysis to identify potential causal variants. A population-specific haplotype pattern was revealed based on six OPRD1 eQTL SNPs and five common haplotypes were identified in a sample of European ancestry (CEU). A European-specific haplotype ('Hap 3') that includes SNPs previously associated with OD and is tagged by SNP rs2236861 is more common in subjects with OD. It is quite common (10%) in CEU but is absent in the African sample (YRI) and extends upstream of OPRD1. SNP rs2236857 is most probably a non-causal variant in LD with the causal SNP/s in a population-specific manner. The study provides an explanation for the lack of association in African Americans, despite its high frequency in this population. OD samples homozygous for 'Hap 3' were reanalyzed using a denser coverage of the region and revealed at least 25 potentially regulatory SNPs in high LD. Notably, GTEx data indicate that some of the SNPs are eQTLs for the upstream phosphatase and actin regulator 4 (PHACTR4), in the cortex, and others are eQTLs for OPRD1 and the upstream lncRNA ENSG00000270605, in the cerebellum. The study highlights the limitation of single SNP analysis and the sensitivity of association studies of OPRD1 to a genetic background. It proposes a long-range functional connection between OPRD1 and PHACTR4. PHACTR4, a mediator of cytoskeletal dynamics, may contribute to drug addiction by modulating synaptic plasticity.

Genetic polymorphisms in the opioid receptor delta 1 (OPRD1) gene are associated with methadone dose in methadone maintenance treatment for heroin dependence

Delta opioid receptor (DOR) is well known to be involved in heroin dependence. This study tested the hypothesis that single nucleotide polymorphisms (SNPs) in the opioid receptor delta 1 (OPRD1) gene coding region are associated with treatment responses in a methadone maintenance therapy (MMT) cohort in Taiwan. Three hundred forty-four MMT patients were recruited. Diastolic/systolic blood pressure, heart rate, methadone dosage, and plasma concentrations of methadone were recorded. Twenty-five SNPs located within the OPRD1 genetic region were selected and genotyped from the genomic DNA of all 344 participants. After pairwise tagger analyses, tagger SNP rs204047 showed a significant association with methadone dosage (P = 0.0019), and tagger SNPs rs204047 and rs797397 were significantly associated with plasma R, S-methadone concentrations (P < 0.0006) in patients tested negative in the urine morphine test, which indicated patients with a better response to MMT. The major genotype carriers showed a higher methadone dosage and higher plasma concentrations of R, S-methadone than the minor genotype carriers. The results indicated that OPRD1 genetic variants were associated with methadone dosage and methadone plasma concentration in MMT patients with a negative morphine test result.

Molecular Imaging of Opioid and Dopamine Systems: Insights Into the Pharmacogenetics of Opioid Use Disorders

Opioid use in the United States has steadily risen since the 1990s, along with staggering increases in addiction and overdose fatalities. With this surge in prescription and illicit opioid abuse, it is paramount to understand the genetic risk factors and neuropsychological effects of opioid use disorder (OUD). Polymorphisms disrupting the opioid and dopamine systems have been associated with increased risk for developing substance use disorders. Molecular imaging studies have revealed how these polymorphisms impact the brain and contribute to cognitive and behavioral differences across individuals. Here, we review the current molecular imaging literature to assess how genetic variations in the opioid and dopamine systems affect function in the brain's reward, cognition, and stress pathways, potentially resulting in vulnerabilities to OUD. Continued research of the functional consequences of genetic variants and corresponding alterations in neural mechanisms will inform prevention and treatment of OUD.