Multi-ancestry study of the genetics of problematic alcohol use in over 1 million individuals.

Problematic alcohol use (PAU), a trait that combines alcohol use disorder and alcohol-related problems assessed with a questionnaire, is a leading cause of death and morbidity worldwide. Here we conducted a large cross-ancestry meta-analysis of PAU in 1,079,947 individuals (European, N = 903,147; African, N = 122,571; Latin American, N = 38,962; East Asian, N = 13,551; and South Asian, N = 1,716 ancestries). We observed a high degree of cross-ancestral similarity in the genetic architecture of PAU and identified 110 independent risk variants in within- and cross-ancestry analyses. Cross-ancestry fine mapping improved the identification of likely causal variants. Prioritizing genes through gene expression and chromatin interaction in brain tissues identified multiple genes associated with PAU. We identified existing medications for potential pharmacological studies by a computational drug repurposing analysis. Cross-ancestry polygenic risk scores showed better performance of association in independent samples than single-ancestry polygenic risk scores. Genetic correlations between PAU and other traits were observed in multiple ancestries, with other substance use traits having the highest correlations. This study advances our knowledge of the genetic etiology of PAU, and these findings may bring possible clinical applicability of genetics insights-together with neuroscience, biology and data science-closer.

Multi-ancestry study of the genetics of problematic alcohol use in >1 million individuals.

Problematic alcohol use (PAU) is a leading cause of death and disability worldwide. To improve our understanding of the genetics of PAU, we conducted a large cross-ancestry meta-analysis of PAU in 1,079,947 individuals. We observed a high degree of cross-ancestral similarity in the genetic architecture of PAU and identified 110 independent risk variants in within- and cross-ancestry analyses. Cross-ancestry fine-mapping improved the identification of likely causal variants. Prioritizing genes through gene expression and/or chromatin interaction in brain tissues identified multiple genes associated with PAU. We identified existing medications for potential pharmacological studies by drug repurposing analysis. Cross-ancestry polygenic risk scores (PRS) showed better performance in independent sample than single-ancestry PRS. Genetic correlations between PAU and other traits were observed in multiple ancestries, with other substance use traits having the highest correlations. The analysis of diverse ancestries contributed significantly to the findings, and fills an important gap in the literature.

Substance use patterns in 9 to 13-year-olds: Longitudinal findings from the Adolescent Brain Cognitive Development (ABCD) study.

Background: Though largely substance-naïve at enrollment, a proportion of the youth in the Adolescent Brain Cognitive Development (ABCD) Study are expected to initiate substance use (SU) as they transition into later adolescence. With annual data from youth 9-13 years-old, this study aims to describe their SU patterns over time. Here, prevalence rates of use are reported, along with predicted odds of use while analyzing common risk-factors associated with youth SU. Methods: The ABCD Study® enrolled 11,876 participants at Baseline (ages 9-10) and has followed them annually. Data through half of the third follow-up visit are available (ages 12-13; n = 6,251). SU descriptives for al psychoactive substances over time are outlined. General estimating equations (GEEs) assessed whether sociodemographic factors, internalizing and externalizing symptoms, and parental SU problems were associated with SU between Baseline and Y2 follow-up. Results: Across time, alcohol and nicotine remain the most used substances. Yearly rates of any SU increased (past year use: 13.9% in Y1; 14% Y2, 18.4% Y3). Cumulatively, by Y3, 39.7% of the cohort reported experimenting (e.g., sipping alcohol) with SU within their lifetime, while 7.4% reported a "full use" (a full alcohol drink, nicotine use, cannabis use, or any other SU) in their lifetime (past-year: 1.9% alcohol, 2.1% nicotine, 1.1% cannabis, 1.2% other substances). GEEs revealed ongoing longitudinal associations between sociodemographic factors, greater externalizing symptoms, and parental drug problems with increased odds of initiating SU. Conclusions: As ABCD participants transition into their teenage years, the cohort is initiating SU at increasing (though still low) rates.

Temporal trends in smoking and nicotine dependence in relation to co-occurring substance use in the United States, 2005-2016.

BACKGROUND: Despite an overall decline in tobacco use in the United States, secular trends of smoking and nicotine dependence with co-occurring substance use are not well characterized. METHODS: We examined self-reported tobacco and other substance use in 22,245 participants age 21-59 in the United States from six waves of the National Health and Nutrition Examination Survey (NHANES). Using Joinpoint regression, we assessed secular trends of smoking and nicotine dependence as a function of co-occurring use of alcohol, prescription opioids, marijuana/hashish, cocaine/heroin/methamphetamine, or other injection drug use. Multivariable logistic regressions were fitted to identify the potential risk factors. RESULTS: During 2005-2016, the prevalence of current smoking decreased (without co-occurring substance use: 17.0 %-12.7 %; with co-occurring use of one substance: 35.3 % to 24.6 %; with co-occurring use of two or more substances: 53.8 %-42.2 %), and moderate-to-severe nicotine dependence decreased as well (8.0 %-4.2 %, 16.0 %-8.8 %, and 23.9 %-15.7 %, respectively). Smoking and nicotine dependence were more likely in those with co-occurring use of one substance (current smoking: odds ratio [OR] = 2.22, 95 % confidence interval [CI] = 2.01-2.45); nicotine dependence: OR = 1.88, 95 % CI = 1.63-2.17) and in those with co-occurring use of two or more substances (current smoking: OR = 5.25, 95 % CI = 4.63-5.95; nicotine dependence: OR = 3.24, 95 % CI = 2.72-3.87). CONCLUSIONS: Co-occurring substance use was associated with smaller reductions in tobacco use, over time, and with increased odds of nicotine dependence. This suggests that co-occurring substance users should be regarded as a tobacco-related disparity group and prioritized for tobacco control interventions.

AIAP: A Quality Control and Integrative Analysis Package to Improve ATAC-seq Data Analysis.

Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) is a technique widely used to investigate genome-wide chromatin accessibility. The recently published Omni-ATAC-seq protocol substantially improves the signal/noise ratio and reduces the input cell number. High-quality data are critical to ensure accurate analysis. Several tools have been developed for assessing sequencing quality and insertion size distribution for ATAC-seq data; however, key quality control (QC) metrics have not yet been established to accurately determine the quality of ATAC-seq data. Here, we optimized the analysis strategy for ATAC-seq and defined a series of QC metrics for ATAC-seq data, including reads under peak ratio (RUPr), background (BG), promoter enrichment (ProEn), subsampling enrichment (SubEn), and other measurements. We incorporated these QC tests into our recently developed ATAC-seq Integrative Analysis Package (AIAP) to provide a complete ATAC-seq analysis system, including quality assurance, improved peak calling, and downstream differential analysis. We demonstrated a significant improvement of sensitivity (20%-60%) in both peak calling and differential analysis by processing paired-end ATAC-seq datasets using AIAP. AIAP is compiled into Docker/Singularity, and it can be executed by one command line to generate a comprehensive QC report. We used ENCODE ATAC-seq data to benchmark and generate QC recommendations, and developed qATACViewer for the user-friendly interaction with the QC report. The software, source code, and documentation of AIAP are freely available at https://github.com/Zhang-lab/ATAC-seq_QC_analysis.

Genome-wide association meta-analysis of nicotine metabolism and cigarette consumption measures in smokers of European descent.

Smoking behaviors, including amount smoked, smoking cessation, and tobacco-related diseases, are altered by the rate of nicotine clearance. Nicotine clearance can be estimated using the nicotine metabolite ratio (NMR) (ratio of 3'hydroxycotinine/cotinine), but only in current smokers. Advancing the genomics of this highly heritable biomarker of CYP2A6, the main metabolic enzyme for nicotine, will also enable investigation of never and former smokers. We performed the largest genome-wide association study (GWAS) to date of the NMR in European ancestry current smokers (n = 5185), found 1255 genome-wide significant variants, and replicated the chromosome 19 locus. Fine-mapping of chromosome 19 revealed 13 putatively causal variants, with nine of these being highly putatively causal and mapping to CYP2A6, MAP3K10, ADCK4, and CYP2B6. We also identified a putatively causal variant on chromosome 4 mapping to TMPRSS11E and demonstrated an association between TMPRSS11E variation and a UGT2B17 activity phenotype. Together the 14 putatively causal SNPs explained ~38% of NMR variation, a substantial increase from the ~20 to 30% previously explained. Our additional GWASs of nicotine intake biomarkers showed that cotinine and smoking intensity (cotinine/cigarettes per day (CPD)) shared chromosome 19 and chromosome 4 loci with the NMR, and that cotinine and a more accurate biomarker, cotinine + 3'hydroxycotinine, shared a chromosome 15 locus near CHRNA5 with CPD and Pack-Years (i.e., cumulative exposure). Understanding the genetic factors influencing smoking-related traits facilitates epidemiological studies of smoking and disease, as well as assists in optimizing smoking cessation support, which in turn will reduce the enormous personal and societal costs associated with smoking.

Marital status, partner acknowledgment of paternity, and neighborhood influences on smoking during first pregnancy: findings across race/ethnicity in linked administrative and census data.

BACKGROUND: Improving prediction of cigarette smoking during pregnancy (SDP), including differences by race/ethnicity and geography, is necessary for interventions to achieve greater and more equitable SDP reductions. METHODS: Using individual-level data on singleton first births, 2010-2017 (N = 182,894), in a US state with high SDP rates, we predicted SDP risk as a function of reproductive partner relationship (marital status, paternity acknowledgement), maternal and residential census tract sociodemographics, and census tract five-year SDP rate. RESULTS: SDP prevalence was 12.7% (white non-Hispanics, WNH), 6.8% (Black/African Americans, AA), 19.5% (Native American, NA), 4.7% (Hispanic, H), and 2.8% (Asian, AS). In WNH and AA, with similar trends in other groups, after adjustment for non-linear effects of maternal age and education and for census tract risk-factors, there was a consistent risk-ordering of SDP rates by reproductive partner relationship: married/with paternity acknowledged < unmarried/acknowledged < unmarried/unacknowledged < married/unacknowledged. Associations with census tract SDP rate, adjusted for maternal and census tract sociodemographics, were stronger for AA and H (OR 2.65-2.67) than for NA (OR = 1.91), WNH (OR = 1.75), or AS (NS). AA SDP was increased in tracts having a higher proportion of WNH residents and was reduced in comparison with WNH at every combination of age, education and partner relationship. CONCLUSIONS: Inattention to differences by race/ethnicity may obscure SDP risk factors. Despite marked race/ethnic differences in unmarried-partner cohabitation rates, failure to acknowledge paternity emerged as an important and consistent risk-predictor. Census-tract five-year SDP rates have heterogeneous origins, but the association of AA SDP risk with increased racial heterogeneity suggests an important influence of neighbor risk behaviors.

Genetic aetiology of self-harm ideation and behaviour.

Family studies have identified a heritable component to self-harm that is partially independent from comorbid psychiatric disorders. However, the genetic aetiology of broad sense (non-suicidal and suicidal) self-harm has not been characterised on the molecular level. In addition, controversy exists about the degree to which suicidal and non-suicidal self-harm share a common genetic aetiology. In the present study, we conduct genome-wide association studies (GWAS) on lifetime self-harm ideation and self-harm behaviour (i.e. any lifetime self-harm act regardless of suicidal intent) using data from the UK Biobank (n > 156,000). We also perform genome wide gene-based tests and characterize the SNP heritability and genetic correlations between these traits. Finally, we test whether polygenic risk scores (PRS) for self-harm ideation and self-harm behaviour predict suicide attempt, suicide thoughts and non-suicidal self-harm (NSSH) in an independent target sample of 8,703 Australian adults. Our GWAS results identified one genome-wide significant locus associated with each of the two phenotypes. SNP heritability (hsnp2) estimates were ~10%, and both traits were highly genetically correlated (LDSC rg > 0.8). Gene-based tests identified seven genes associated with self-harm ideation and four with self-harm behaviour. Furthermore, in the target sample, PRS for self-harm ideation were significantly associated with suicide thoughts and NSSH, and PRS for self-harm behaviour predicted suicide thoughts and suicide attempt. Follow up regressions identified a shared genetic aetiology between NSSH and suicide thoughts, and between suicide thoughts and suicide attempt. Evidence for shared genetic aetiology between NSSH and suicide attempt was not statistically significant.

Eating disorders in a community-based sample of women with alcohol use disorder and nicotine dependence.

BACKGROUND: Studies consistently report a higher prevalence of substance use disorders (SUDs) among women with eating disorders than control women. However, limited research exists on the prevalence of eating disorder symptoms and diagnoses in women with SUDs, especially in community-based populations. We examined the prevalence of eating disorder symptoms and diagnosis by the presence or absence of lifetime alcohol use disorder (AUD) and/or nicotine dependence (ND) in a community-based sample of women. METHODS: 3756 women (median age = 22 years) from the Missouri Adolescent Female Twin Study completed a modified semi-structured interview assessing lifetime DSM-IV psychiatric disorders and SUDs. Logistic regression models adjusted for demographic characteristics and other psychopathology, and robust standard errors accounted for the non-independence of twin data. RESULTS: In general, women with comorbid AUD and ND had a higher prevalence of eating disorder symptoms and diagnoses than women with AUD or ND Only, who in turn had a higher prevalence than those without either SUD. After adjustment for covariates, women with AUD and ND had significantly greater risk of broad anorexia nervosa (RRR = 3.17; 99 % CI = 1.35, 7.44), purging disorder (2.59; 1.24, 5.43), and numerous eating disorder symptoms than women with neither disorder. Significant differences emerged between individuals with both AUD and ND versus women with AUD Only or ND Only for some eating disorder symptoms. CONCLUSIONS: Women with lifetime AUD or ND diagnoses are at high risk for eating disorder symptoms and diagnoses, underscoring the importance of assessing eating disorder symptoms among women with these disorders.

Leveraging genome-wide data to investigate differences between opioid use vs. opioid dependence in 41,176 individuals from the Psychiatric Genomics Consortium.

To provide insights into the biology of opioid dependence (OD) and opioid use (i.e., exposure, OE), we completed a genome-wide analysis comparing 4503 OD cases, 4173 opioid-exposed controls, and 32,500 opioid-unexposed controls, including participants of European and African descent (EUR and AFR, respectively). Among the variants identified, rs9291211 was associated with OE (exposed vs. unexposed controls; EUR z = -5.39, p = 7.2 × 10-8). This variant regulates the transcriptomic profiles of SLC30A9 and BEND4 in multiple brain tissues and was previously associated with depression, alcohol consumption, and neuroticism. A phenome-wide scan of rs9291211 in the UK Biobank (N > 360,000) found association of this variant with propensity to use dietary supplements (p = 1.68 × 10-8). With respect to the same OE phenotype in the gene-based analysis, we identified SDCCAG8 (EUR + AFR z = 4.69, p = 10-6), which was previously associated with educational attainment, risk-taking behaviors, and schizophrenia. In addition, rs201123820 showed a genome-wide significant difference between OD cases and unexposed controls (AFR z = 5.55, p = 2.9 × 10-8) and a significant association with musculoskeletal disorders in the UK Biobank (p = 4.88 × 10-7). A polygenic risk score (PRS) based on a GWAS of risk-tolerance (n = 466,571) was positively associated with OD (OD vs. unexposed controls, p = 8.1 × 10-5; OD cases vs. exposed controls, p = 0.054) and OE (exposed vs. unexposed controls, p = 3.6 × 10-5). A PRS based on a GWAS of neuroticism (n = 390,278) was positively associated with OD (OD vs. unexposed controls, p = 3.2 × 10-5; OD vs. exposed controls, p = 0.002) but not with OE (p = 0.67). Our analyses highlight the difference between dependence and exposure and the importance of considering the definition of controls in studies of addiction.

Alcohol Dependence and Reproductive Onset in Women, Updated: Analyses of Research and State-Level Administrative Data.

OBJECTIVE: The present study updates prior research, incorporating state-level administrative data to examine associations between self-reported history of alcohol dependence and birth record-derived reproductive onset, the latter assessed through peak childbearing years. METHOD: Participants included 542 African ancestry (AA) and 2,928 European or other ancestry (EA) female twins ascertained through Missouri birth records and recruited as part of a birth cohort study of like-sex female pairs born between 1975 and 1985. Analyses were limited to twins for whom residence in Missouri when of reproductive age could be documented, including twins who left Missouri but later returned. Cox proportional hazards regression models were estimated predicting age at first childbirth from history of alcohol dependence, separately for AA and EA twins, without and with adjustment for sociodemographic characteristics, comorbid psychopathology and other substance involvement, overweight/obesity status, and family-of-origin and childhood risk factors. RESULTS: Among EA twins, alcohol dependence predicted both early and delayed childbearing; in adjusted models, alcohol dependence was associated with overall delayed childbearing. Associations between alcohol dependence and reproductive onset were nonsignificant among AA twins. CONCLUSIONS: Findings for EA twins are consistent with the broader literature indicating increased risk of teen motherhood associated with early-onset and problem drinking, but suggest that this may be explained by other correlated risk factors. The more robust finding, confirming relatively recent research, is of delayed childbearing associated with alcohol dependence.

Genomic prediction of alcohol-related morbidity and mortality.

While polygenic risk scores (PRS) have been shown to predict many diseases and risk factors, the potential of genomic prediction in harm caused by alcohol use has not yet been extensively studied. Here, we built a novel polygenic risk score of 1.1 million variants for alcohol consumption and studied its predictive capacity in 96,499 participants from the FinnGen study and 39,695 participants from prospective cohorts with detailed baseline data and up to 25 years of follow-up time. A 1 SD increase in the PRS was associated with 11.2 g (=0.93 drinks) higher weekly alcohol consumption (CI = 9.85-12.58 g, p = 2.3 × 10-58). The PRS was associated with alcohol-related morbidity (4785 incident events) and the risk estimate between the highest and lowest quintiles of the PRS was 1.83 (95% CI = 1.66-2.01, p = 1.6 × 10-36). When adjusted for self-reported alcohol consumption, education, marital status, and gamma-glutamyl transferase blood levels in 28,639 participants with comprehensive baseline data from prospective cohorts, the risk estimate between the highest and lowest quintiles of the PRS was 1.58 (CI = 1.26-1.99, p = 8.2 × 10-5). The PRS was also associated with all-cause mortality with a risk estimate of 1.33 between the highest and lowest quintiles (CI = 1.20-1.47, p = 4.5 × 10-8) in the adjusted model. In conclusion, the PRS for alcohol consumption independently associates for both alcohol-related morbidity and all-cause mortality. Together, these findings underline the importance of heritable factors in alcohol-related health burden while highlighting how measured genetic risk for an important behavioral risk factor can be used to predict related health outcomes.

Genome-Wide Meta-Analyses of FTND and TTFC Phenotypes.

INTRODUCTION: FTND (FagerstrÓ§m test for nicotine dependence) and TTFC (time to smoke first cigarette in the morning) are common measures of nicotine dependence (ND). However, genome-wide meta-analysis for these phenotypes has not been reported. METHODS: Genome-wide meta-analyses for FTND (N = 19,431) and TTFC (N = 18,567) phenotypes were conducted for adult smokers of European ancestry from 14 independent cohorts. RESULTS: We found that SORBS2 on 4q35 (p = 4.05 × 10-8), BG182718 on 11q22 (p = 1.02 × 10-8), and AA333164 on 14q21 (p = 4.11 × 10-9) were associated with TTFC phenotype. We attempted replication of leading candidates with independent samples (FTND, N = 7010 and TTFC, N = 10 061), however, due to limited power of the replication samples, the replication of these new loci did not reach significance. In gene-based analyses, COPB2 was found associated with FTND phenotype, and TFCP2L1, RELN, and INO80C were associated with TTFC phenotype. In pathway and network analyses, we found that the interconnected interactions among the endocytosis, regulation of actin cytoskeleton, axon guidance, MAPK signaling, and chemokine signaling pathways were involved in ND. CONCLUSIONS: Our analyses identified several promising candidates for both FTND and TTFC phenotypes, and further verification of these candidates was necessary. Candidates supported by both FTND and TTFC (CHRNA4, THSD7B, RBFOX1, and ZNF804A) were associated with addiction to alcohol, cocaine, and heroin, and were associated with autism and schizophrenia. We also identified novel pathways involved in cigarette smoking. The pathway interactions highlighted the importance of receptor recycling and internalization in ND. IMPLICATIONS: Understanding the genetic architecture of cigarette smoking and ND is critical to develop effective prevention and treatment. Our study identified novel candidates and biological pathways involved in FTND and TTFC phenotypes, and this will facilitate further investigation of these candidates and pathways.

Author Correction: GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal effect of schizophrenia liability.

Several occurrences of the word 'schizophrenia' have been re-worded as 'liability to schizophrenia' or 'schizophrenia risk', including in the title, which should have been "GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal effect of schizophrenia liability," as well as in Supplementary Figures 1-10 and Supplementary Tables 7-10, to more accurately reflect the findings of the work.

The interaction of sociodemographic risk factors and measures of nicotine dependence in predicting maternal smoking during pregnancy.

BACKGROUND: Understanding differences in nicotine dependence assessments' ability to predict smoking cessation is complicated by variation in quit attempt contexts. Pregnancy reduces this variation, as each pregnant smoker receives the same strong cessation incentive. Cigarette smoking during pregnancy (SDP) provides a powerful paradigm for analyzing the interplay between nicotine dependence measures and sociodemographics in predicting cessation failure. METHODS: Data from a female twin cohort (median birth year 1980), assessed in teens and early twenties, were merged with birth records to identify those with smoking history who experienced childbirth (N = 1657 births, N = 763 mothers). Logistic regression predicting SDP, as a function of birth record sociodemographic variables, generated a sociodemographic risk-score. Further analysis incorporated the risk-score with data from research interviews on DSM-IV-Nicotine Dependence symptom count, Heaviness of Smoking Index. RESULTS: Low maternal educational level, younger age at childbirth, and being unmarried all contributed risk for SDP. In addition to sociodemographic risk-score, the best predictors of SDP included HSI-score (OR:1.51), their two-way interaction (OR:0.39; reduced impact of dependence at intermediate-high sociodemographic risk), history of ≥ two failed quit attempts (OR:1.38), and a dummy variable for prior pregnancy at time of assessment (OR:1.82). DSM-IV-Nicotine Dependence symptoms underperformed the Heaviness of Smoking Index and did not improve prediction when added to the best model. CONCLUSIONS: The 2-item Heaviness of Smoking Index measure and report of ≥ two failed quit attempts performed best for predicting SDP. The contribution of either nicotine dependence measure to SDP risk was diminished at increased levels of sociodemographic risk.

Quantifying between-cohort and between-sex genetic heterogeneity in major depressive disorder.

Major depressive disorder (MDD) is clinically heterogeneous with prevalence rates twice as high in women as in men. There are many possible sources of heterogeneity in MDD most of which are not measured in a sufficiently comparable way across study samples. Here, we assess genetic heterogeneity based on two fundamental measures, between-cohort and between-sex heterogeneity. First, we used genome-wide association study (GWAS) summary statistics to investigate between-cohort genetic heterogeneity using the 29 research cohorts of the Psychiatric Genomics Consortium (PGC; N cases = 16,823, N controls = 25,632) and found that some of the cohort heterogeneity can be attributed to ascertainment differences (such as recruitment of cases from hospital vs. community sources). Second, we evaluated between-sex genetic heterogeneity using GWAS summary statistics from the PGC, Kaiser Permanente GERA, UK Biobank, and the Danish iPSYCH studies but did not find convincing evidence for genetic differences between the sexes. We conclude that there is no evidence that the heterogeneity between MDD data sets and between sexes reflects genetic heterogeneity. Larger sample sizes with detailed phenotypic records and genomic data remain the key to overcome heterogeneity inherent in assessment of MDD.

Trans-ethnic kidney function association study reveals putative causal genes and effects on kidney-specific disease aetiologies.

Chronic kidney disease (CKD) affects ~10% of the global population, with considerable ethnic differences in prevalence and aetiology. We assemble genome-wide association studies of estimated glomerular filtration rate (eGFR), a measure of kidney function that defines CKD, in 312,468 individuals of diverse ancestry. We identify 127 distinct association signals with homogeneous effects on eGFR across ancestries and enrichment in genomic annotations including kidney-specific histone modifications. Fine-mapping reveals 40 high-confidence variants driving eGFR associations and highlights putative causal genes with cell-type specific expression in glomerulus, and in proximal and distal nephron. Mendelian randomisation supports causal effects of eGFR on overall and cause-specific CKD, kidney stone formation, diastolic blood pressure and hypertension. These results define novel molecular mechanisms and putative causal genes for eGFR, offering insight into clinical outcomes and routes to CKD treatment development.

Genome-wide association study in Finnish twins highlights the connection between nicotine addiction and neurotrophin signaling pathway.

The heritability of nicotine dependence based on family studies is substantial. Nevertheless, knowledge of the underlying genetic architecture remains meager. Our aim was to identify novel genetic variants responsible for interindividual differences in smoking behavior. We performed a genome-wide association study on 1715 ever smokers ascertained from the population-based Finnish Twin Cohort enriched for heavy smoking. Data imputation used the 1000 Genomes Phase I reference panel together with a whole genome sequence-based Finnish reference panel. We analyzed three measures of nicotine addiction-smoking quantity, nicotine dependence and nicotine withdrawal. We annotated all genome-wide significant SNPs for their functional potential. First, we detected genome-wide significant association on 16p12 with smoking quantity (P = 8.5 × 10-9 ), near CLEC19A. The lead-SNP stands 22 kb from a binding site for NF-κB transcription factors, which play a role in the neurotrophin signaling pathway. However, the signal was not replicated in an independent Finnish population-based sample, FINRISK (n = 6763). Second, nicotine withdrawal showed association on 2q21 in an intron of TMEM163 (P = 2.1 × 10-9 ), and on 11p15 (P = 6.6 × 10-8 ) in an intron of AP2A2, and P = 4.2 × 10-7 for a missense variant in MUC6, both involved in the neurotrophin signaling pathway). Third, association was detected on 3p22.3 for maximum number of cigarettes smoked per day (P = 3.1 × 10-8 ) near STAC. Associating CLEC19A and TMEM163 SNPs were annotated to influence gene expression or methylation. The neurotrophin signaling pathway has previously been associated with smoking behavior. Our findings further support the role in nicotine addiction.

Common genetic contributions to high-risk trauma exposure and self-injurious thoughts and behaviors.

BACKGROUND: Prior research has documented shared heritable contributions to non-suicidal self-injury (NSSI) and suicidal ideation (SI) as well as NSSI and suicide attempt (SA). In addition, trauma exposure has been implicated in risk for NSSI and suicide. Genetically informative studies are needed to determine common sources of liability to all three self-injurious thoughts and behaviors, and to clarify the nature of their associations with traumatic experiences. METHODS: Multivariate biometric modeling was conducted using data from 9526 twins [59% female, mean age = 31.7 years (range 24-42)] from two cohorts of the Australian Twin Registry, some of whom also participated in the Childhood Trauma Study and the Nicotine Addiction Genetics Project. RESULTS: The prevalences of high-risk trauma exposure (HRT), NSSI, SI, and SA were 24.4, 5.6, 27.1, and 4.6%, respectively. All phenotypes were moderately to highly correlated. Genetic influences on self-injurious thoughts and behaviors and HRT were significant and highly correlated among men [rG = 0.59, 95% confidence interval (CI) (0.37-0.81)] and women [rG = 0.56 (0.49-0.63)]. Unique environmental influences were modestly correlated in women [rE = 0.23 (0.01-0.45)], suggesting that high-risk trauma may confer some direct risk for self-injurious thoughts and behaviors among females. CONCLUSIONS: Individuals engaging in NSSI are at increased risk for suicide, and common heritable factors contribute to these associations. Preventing trauma exposure may help to mitigate risk for self-harm and suicide, either directly or indirectly via reductions in liability to psychopathology more broadly. In addition, targeting pre-existing vulnerability factors could significantly reduce risk for life-threatening behaviors among those who have experienced trauma.

Biomarker and Genomic Risk Factors for Liver Function Test Abnormality in Hazardous Drinkers.

BACKGROUND: Alcohol dependence and long-term excessive alcohol use may cause liver damage, but only some patients develop cirrhosis. Similarly, high alcohol intake without evident liver disease often but not always produces abnormal enzymatic liver function tests (LFTs), particularly gamma-glutamyl transferase (GGT). We postulate that the factors predisposing to cirrhosis in alcoholics and to liver enzyme abnormality in drinkers are similar, and that biochemical LFTs could therefore be useful as markers of risk of alcoholic liver disease in excessive drinkers. METHODS: Data from participants in twin and twin-family studies on alcohol use and dependence were used to identify 1,003 people who had reported excessive alcohol intake (28 drinks or more per week). A total of 962 of these provided blood for biochemical tests at the same time. Body mass index (BMI) and biomarkers of metabolic syndrome, inflammation, and iron stores were used in logistic regression with abnormality in serum GGT, alanine aminotransferase (ALT), or aspartate aminotransferase (AST) as outcomes. We conducted genome-wide association analyses for GGT, ALT, and AST separately in the group reporting excessive alcohol intake (N = 951) and a low-intake group reporting 14 drinks or fewer per week (N = 8,716), and compared results. RESULTS: Abnormal GGT and ALT among excessive drinkers were associated with higher BMI, triglycerides, insulin, uric acid, C-reactive protein, ferritin, and transferrin saturation; and with lower high-density-lipoprotein cholesterol. Abnormal AST was associated with triglycerides, ferritin, and transferrin saturation. ALT was significantly associated with variants at reported genetic loci for alcoholic liver disease (PNPLA3, rs738409, p = 0.0076; TM6SF2, rs10401969, p = 0.0076; HSD17B13, rs10433879, p = 0.0024). CONCLUSIONS: Known risk factors for alcoholic cirrhosis including obesity and markers of metabolic syndrome, iron overload and inflammation are associated with liver enzyme abnormality in excessive drinkers.