Effects of acute ethanol exposure on anxiety measures and epigenetic modifiers in the extended amygdala of adolescent rats. Sakharkar Amul J,Tang Lei,Zhang Huaibo,Chen Ying,Grayson Dennis R,Pandey Subhash C The international journal of neuropsychopharmacology Epigenetic mechanisms appear to play an important role in neurodevelopment. We investigated the effects of acute ethanol exposure on anxiety measures and function of histone deacetylases (HDAC) and DNA methyltransferases (DNMT) in the amygdala and bed nucleus of stria terminalis (BNST) of adolescent rats. One hour after ethanol exposure, rats were subjected to anxiety measures. A subset of adolescent rats was exposed to two doses (24 h apart) of ethanol (2 g/kg) to measure rapid ethanol tolerance to anxiolysis. The HDAC and DNMT activities and mRNA levels of DNMT isoforms were measured in the amygdala and BNST. The lower dose of ethanol (1 g/kg) produced neither anxiolysis, nor inhibited the HDAC and DNMT activities in the amygdala and BNST, except DNMT activity in BNST was attenuated. Anxiolysis by ethanol was observed at 2 and 2.25 g/kg, whereas higher doses (2.5 and 3 g/kg) were found to be sedative. DNMT activity in the amygdala and BNST, and nuclear HDAC activity in the amygdala, but not in the BNST were also inhibited by these doses of ethanol. A lack of tolerance was observed on ethanol-induced inhibition of DNMT activity in the amygdala and BNST, and nuclear HDAC activity in the amygdala, as well to anxiolysis produced by ethanol (2 g/kg). The DNMT1, DNMT3a, and DNMT3b mRNA expression in the amygdala was not affected by either 1or 2 doses of 2 g/kg. However, DNMT1 and DNMT3a expression in the BNST was increased, whereas DNMT3l mRNA was decreased in the amygdala, after 2 doses of 2 g/kg ethanol. These results suggest that reduced sensitivity to anxiolysis and the lack of rapid tolerance to the anxiolytic effects of ethanol and inhibition of HDAC and DNMT functions may play a role in engaging adolescents in binge drinking patterns. 10.1017/S1461145714001047
    Adolescent binge-pattern alcohol exposure alters genome-wide DNA methylation patterns in the hypothalamus of alcohol-naïve male offspring. Asimes AnnaDorothea,Torcaso Audrey,Pinceti Elena,Kim Chun K,Zeleznik-Le Nancy J,Pak Toni R Alcohol (Fayetteville, N.Y.) Teenage binge drinking is a major health concern in the United States, with 21% of teenagers reporting binge-pattern drinking behavior in the previous 30 days. Recently, our lab showed that alcohol-naïve offspring of rats exposed to alcohol during adolescence exhibited altered gene expression profiles in the hypothalamus, a brain region involved in stress regulation. We employed Enhanced Reduced Representation Bisulfite Sequencing as an unbiased approach to test the hypothesis that parental exposure to binge-pattern alcohol during adolescence alters DNA methylation profiles in their alcohol-naïve offspring. Wistar rats were administered a repeated binge-ethanol exposure paradigm during early (postnatal day (PND) 37-44) and late (PND 67-74) adolescent development. Animals were mated 24 h after the last ethanol dose and subsequent offspring were produced. Analysis of male PND7 offspring revealed that offspring of alcohol-exposed parents exhibited differential DNA methylation patterns in the hypothalamus. The differentially methylated cytosines (DMCs) were distinct between offspring depending on which parent was exposed to ethanol. Moreover, novel DMCs were observed when both parents were exposed to ethanol and many DMCs from single parent ethanol exposure were not recapitulated with dual parent exposure. We also measured mRNA expression of several differentially methylated genes and some, but not all, showed correlative changes in expression. Importantly, methylation was not a direct predictor of expression levels, underscoring the complexity of transcriptional regulation. Overall, we demonstrate that adolescent binge ethanol exposure causes altered genome-wide DNA methylation patterns in the hypothalamus of alcohol-naïve offspring. 10.1016/j.alcohol.2016.10.010
    Focus on: epigenetics and fetal alcohol spectrum disorders. Kobor Michael S,Weinberg Joanne Alcohol research & health : the journal of the National Institute on Alcohol Abuse and Alcoholism Epigenetic changes-stable but potentially reversible alterations in a cell's genetic information that result in changes in gene expression but do not involve changes in the underlying DNA sequence-may mediate some of the detrimental effects of prenatal alcohol exposure and contribute to the deficits and abnormalities associated with fetal alcohol spectrum disorders. These epigenetic processes are linked to the chromatin (i.e., DNA, histone proteins, and other associated proteins) and commonly involve chemical modifications (e.g., methylation) of these molecules, which may result in altered expression of the affected genes. Even alcohol exposure prior to conception appears to be able to induce epigenetic changes in the parental genetic material that can be passed on to the offspring and affect offspring outcome. Similarly, epigenetic processes may occur as a result of maternal alcohol consumption during the period between fertilization of the egg and implantation in the uterus. The period most sensitive to alcohol's adverse effects appears to be gastrulation, which corresponds to prenatal weeks 3 to 8 in the human and prenatal days 7 to 14 in the mouse, when cells are differentiating to form organs. One way in which alcohol exposure may induce epigenetic changes, particularly abnormal DNA methylation, is by affecting a set of biochemical reactions called the methionine-homocysteine cycle.
    DNA methylation and substance-use risk: a prospective, genome-wide study spanning gestation to adolescence. Cecil C A M,Walton E,Smith R G,Viding E,McCrory E J,Relton C L,Suderman M,Pingault J-B,McArdle W,Gaunt T R,Mill J,Barker E D Translational psychiatry Epigenetic processes have been implicated in addiction; yet, it remains unclear whether these represent a risk factor and/or a consequence of substance use. Here, we believe we conducted the first genome-wide, longitudinal study to investigate whether DNA methylation patterns in early life prospectively associate with substance use in adolescence. The sample comprised of 244 youth (51% female) from the Avon Longitudinal Study of Parents and Children (ALSPAC), with repeated assessments of DNA methylation (Illumina 450k array; cord blood at birth, whole blood at age 7) and substance use (tobacco, alcohol and cannabis use; age 14-18). We found that, at birth, epigenetic variation across a tightly interconnected genetic network (n=65 loci; q<0.05) associated with greater levels of substance use during adolescence, as well as an earlier age of onset amongst users. Associations were specific to the neonatal period and not observed at age 7. Key annotated genes included PACSIN1, NEUROD4 and NTRK2, implicated in neurodevelopmental processes. Several of the identified loci were associated with known methylation quantitative trait loci, and consequently likely to be under significant genetic control. Collectively, these 65 loci were also found to partially mediate the effect of prenatal maternal tobacco smoking on adolescent substance use. Together, findings lend novel insights into epigenetic correlates of substance use, highlight birth as a potentially sensitive window of biological vulnerability and provide preliminary evidence of an indirect epigenetic pathway linking prenatal tobacco exposure and adolescent substance use. 10.1038/tp.2016.247
    Investigating the impact of cigarette smoking behaviours on DNA methylation patterns in adolescence. Prince Claire,Hammerton Gemma,Taylor Amy E,Anderson Emma L,Timpson Nicholas J,Davey Smith George,Munafò Marcus R,Relton Caroline L,Richmond Rebecca C Human molecular genetics Smoking usually begins in adolescence, and early onset of smoking has been linked to increased risk of later life disease. There is a need to better understand the biological impact of cigarette smoking behaviours in adolescence. DNA methylation profiles related to smoking behaviours and cessation in adulthood have been previously identified, but alterations arising from smoking initiation have not been thoroughly investigated. We aimed to investigate DNA methylation in the Avon Longitudinal Study of Parents and Children in relation to (1) different smoking measures, (2) time since smoking initiation and frequency of smoke exposure and (3) latent classes of smoking behaviour. Using 2620 CpG sites previously associated with cigarette smoking, we investigated DNA methylation change in relation to own smoking measures, smoke exposure duration and frequency, and using longitudinal latent class analysis of different smoking behaviour patterns in 968 adolescents. Eleven CpG sites located in seven gene regions were differentially methylated in relation to smoking in adolescence. While only AHRR (cg05575921) showed a robust pattern of methylation in relation to weekly smoking, several CpGs showed differences in methylation among individuals who had tried smoking compared with non-smokers. In relation to smoke exposure duration and frequency, cg05575921 showed a strong dose-response relationship, while there was evidence for more immediate methylation change at other sites. Our findings illustrate the impact of cigarette smoking behaviours on DNA methylation at some smoking-responsive CpG sites, even among individuals with a short smoking history. 10.1093/hmg/ddy316
    Drinking beyond a lifetime: New and emerging insights into paternal alcohol exposure on subsequent generations. Finegersh Andrey,Rompala Gregory R,Martin David I K,Homanics Gregg E Alcohol (Fayetteville, N.Y.) Alcohol-use disorder (AUD) is prevalent and associated with substantial socioeconomic costs. While heritability estimates of AUD are ∼50%, identifying specific gene variants associated with risk for AUD has proven challenging despite considerable investment. Emerging research into heritability of complex diseases has implicated transmission of epigenetic variants in the development of behavioral phenotypes, including drug preference and drug-induced behavior. Several recent rodent studies have specifically focused on paternal transmission of epigenetic variants, which is especially relevant because sires are not present for offspring rearing and changes to offspring phenotype are assumed to result from modifications to the sperm epigenome. While considerable interest in paternal transmission of epigenetic variants has emerged recently, paternal alcohol exposures have been studied for 30+ years with interesting behavioral and physiologic effects noted on offspring. However, only recently, with improvements in technology to identify epigenetic modifications in germ cells, has it been possible to identify mechanisms by which paternal ethanol exposure alters offspring behavior. This review presents an overview of epigenetic inheritance in the context of paternal ethanol exposure and suggests future studies to identify specific effects of paternal ethanol exposure on offspring behavior and response to ethanol. 10.1016/j.alcohol.2015.02.008
    Binge Drinking and Intergenerational Implications: Parental Preconception Alcohol Impacts Offspring Development in Rats. Asimes AnnaDorothea,Kim Chun K,Cuarenta Amelia,Auger Anthony P,Pak Toni R Journal of the Endocrine Society Preconception behaviors and experiences of mothers and fathers can affect future offspring. Recently, our laboratory showed that alcohol-naive offspring of parents who were exposed to repeated binge alcohol during adolescence showed altered DNA methylation patterns in the hypothalamus, a brain region involved in regulation of pubertal development, stress, and behavior. These observations have potentially far-reaching consequences for human health, as more than 4.6 million Americans under the age of 21 years report engaging in the rapid intoxication behavior of binge-pattern alcohol (EtOH) drinking. Therefore, we tested the hypothesis that offspring of binge EtOH‒exposed parents would have altered hypothalamic function manifested phenotypically as improper pubertal development, impaired socialization, and dysregulated stress response. In addition, we tested the hypothesis that parental EtOH exposure would confer adaptive protection from the negative effects of EtOH when offspring were themselves exposed to EtOH. Rats received EtOH via oral gavage once daily for 6 days at both early [postnatal day (PND) 37] and late puberty (PND 67). Animals were paired (EtOH-EtOH, vehicle-vehicle) for mating 24 hours after the last EtOH dose. After weaning, offspring were randomized to vehicle treatment to assess changes in normal development or to EtOH treatment to assess the effect of parental EtOH exposure on offspring response to this treatment. We found that offspring had smaller body weights and displayed fewer play behaviors when parents had been exposed to EtOH before conception. In addition, offspring showed a reduction in pubertal development markers that could indicate that parental preconception EtOH exposure confers maladaptive epigenetic traits in first-generation offspring. 10.1210/js.2018-00051
    Changes in the methylation status of DAT, SERT, and MeCP2 gene promoters in the blood cell in families exposed to alcohol during the periconceptional period. Lee Bom-Yi,Park So-Yeon,Ryu Hyun-Mee,Shin Chan-Young,Ko Ki-Nam,Han Jung-Yeol,Koren Gideon,Cho Youl-Hee Alcoholism, clinical and experimental research BACKGROUND:Alcohol exposure has been shown to cause devastating effects on neurobehavioral development in numerous animal and human studies. The alteration of DNA methylation levels in gene-specific promoter regions has been investigated in some studies of human alcoholics. This study was aimed to investigate whether social alcohol consumption during periconceptional period is associated with epigenetic alteration and its generational transmission in the blood cells. METHODS:We investigated patterns of alcohol intake in a prospective cohort of 355 pairs of pregnant women and their spouses who reported alcohol intake during the periconceptional period. A subpopulation of 164 families was established for the epigenetic study based on the availability of peripheral blood and cord blood DNA. The relative methylation changes of dopamine transporter (DAT), serotonin transporter (SERT), and methyl CpG binding protein 2 (MeCP2) gene promoters were analyzed using methylation-specific endonuclease digestion followed by quantitative real-time polymerase chain reaction. RESULTS:The relative methylation level of the DAT gene promoter was decreased in the group of mothers reporting above moderate drinking (p = 0.029) and binge drinking (p = 0.037) during pregnancy. The relative methylation level of the DAT promoter was decreased in the group of fathers reporting heavy binge drinking (p = 0.003). The relative methylation levels of the SERT gene promoter were decreased in the group of newborns of light drinking mothers before pregnancy (p = 0.012) and during pregnancy (p = 0.003). The methylation level in the MeCP2 promoter region of babies whose mothers reported above moderate drinking during pregnancy was increased (p = 0.02). In addition, methylation pattern in the DAT promoter region of babies whose fathers reported heavy binge drinking was decreased (p = 0.049). CONCLUSIONS:These findings suggest that periconceptional alcohol intake may cause epigenetic changes in specific locus of parental and newborn genomes as follows: Alcohol consumption decreases the methylation level of the DAT promoter region of the parent themselves, maternal alcohol drinking during the periconceptional period decreases the methylation level of the SERT promoter region of newborns, and maternal alcohol consumption increases the methylation level of the MeCP2 promoter region of newborns. 10.1111/acer.12635
    Impact of nicotine, alcohol, and cocaine exposure on germline integrity and epigenome. Zeid Dana,Gould Thomas J Neuropharmacology Converging evidence suggests that parental exposure to drugs of abuse can affect offspring phenotypes. The impacts of drug abuse on germ cell quality may mediate multigenerational and transgenerational inheritance, although biological pathways underlying this mode of inheritance are not yet characterized. Germline epigenetic marks are modified by drug exposure and have emerged as promising mechanistic candidates in recent work. Drug exposure also impacts overall germline integrity and reproductive functioning, although the role of these consequences in multi/transgenerational inheritance is unclear. This review synthesizes literature on effects of exposure to alcohol, cocaine, and nicotine on the germline with a focus on epigenetic modifications following drug exposure and broader impacts on germline integrity and reproductive functioning. We discuss potential interactions between reproductive functioning, germline integrity, and germline epigenome/transcriptome in pathways underlying multi/transgenerational inheritance. We find that existing data may support independent or interactive contributions of these germline impacts on offspring phenotypes in a manner that may mediate multi/transgenerational inheritance. 10.1016/j.neuropharm.2020.108127
    Prenatal stress leads to chromatin and synaptic remodeling and excessive alcohol intake comorbid with anxiety-like behaviors in adult offspring. Dong Erbo,Guidotti Alessandro,Zhang Huaibo,Pandey Subhash C Neuropharmacology Epidemiologic evidence suggests that individuals during their prenatal development may be especially vulnerable to the effects of environmental factors such as stress that predisposes them to psychiatric disorders including alcohol use disorder (AUD) later in life. Currently, the epigenetic mechanisms of anxiety comorbid with AUD induced by prenatal stress (PRS) remain to be elucidated. Here, we examined anxiety-like and alcohol drinking behaviors in adult offspring of prenatally stressed dam (PRS-mice) using elevated plus maze, light/dark box and two-bottle free-choice paradigm. It was found that PRS-mice exhibit heightened anxiety-like behaviors and increased alcohol intake in adulthood and these behavioral deficits were associated with a significant decrease in dendritic spine density (DSD) in medial prefrontal cortex (mPFC) relative to non-stressed mice (NS mice). To determine the mechanisms by which PRS reduces DSD, we examined the expressions of key genes associated with synaptic plasticity, including activity regulated cytoskeleton associated protein (Arc), spinophilin (Spn), postsynaptic density 95 (Psd95), tropomyosin receptor kinase B (TrkB), protein kinase B (Akt), mammalian target of rapamycin (mTOR) and period 2 (Per2) in mPFC of PRS and NS mice. The mRNA levels of these genes were significantly decreased in PRS mice. Methylated DNA and chromatin immunoprecipitation studies revealed hyper DNA methylation or reduced histone H3K14 acetylation on promoters of above genes suggesting that epigenetic dysregulation may be responsible for the deficits in their expression. Findings from this study suggest that prenatal stress induced abnormal epigenetic mechanisms and synaptic plasticity-related events may be associated with anxiety-like and alcohol drinking behaviors in adulthood. 10.1016/j.neuropharm.2018.07.010
    Paternal alcohol exposure reduces alcohol drinking and increases behavioral sensitivity to alcohol selectively in male offspring. Finegersh Andrey,Homanics Gregg E PloS one Alcohol use disorder (AUD) is heritable, but the genetic basis for this disease remains poorly understood. Although numerous gene variants have been associated with AUD, these variants account for only a small fraction of the total risk. The idea of inheritance of acquired characteristics, i.e. "epigenetic inheritance," is re-emerging as a proven adjunct to traditional modes of genetic inheritance. We hypothesized that alcohol drinking and neurobiological sensitivity to alcohol are influenced by ancestral alcohol exposure. To test this hypothesis, we exposed male mice to chronic vapor ethanol or control conditions, mated them to ethanol-naïve females, and tested adult offspring for ethanol drinking, ethanol-induced behaviors, gene expression, and DNA methylation. We found that ethanol-sired male offspring had reduced ethanol preference and consumption, enhanced sensitivity to the anxiolytic and motor-enhancing effects of ethanol, and increased Bdnf expression in the ventral tegmental area (VTA) compared to control-sired male offspring. There were no differences among ethanol- and control-sired female offspring on these assays. Ethanol exposure also decreased DNA methylation at the BdnfÆpromoter of sire's germ cells and hypomethylation was maintained in the VTA of both male and female ethanol-sired offspring. Our findings show that paternal alcohol exposure is a previously unrecognized regulator of alcohol drinking and behavioral sensitivity to alcohol in male, but not female, offspring. Paternal alcohol exposure also induces epigenetic alterations (DNA hypomethylation) and gene expression changes that persist in the VTA of offspring. These results provide new insight into the inheritance and development of alcohol drinking behaviors. 10.1371/journal.pone.0099078
    Gender differences in the transmission of risk for antisocial behavior problems across generations. Li Pin,Becker Jill B,Heitzeg Mary M,McClellan Michele L,Reed Beth Glover,Zucker Robert A PloS one Previous studies have shown that children of alcohol use disorder (AUD) parents are more likely to develop alcohol problems as well as antisocial and other behavior problems. The purpose of this study was to examine gender discordance in the effect of early maternal and paternal influences on antisocial behaviors of boys and girls, as well as the environmental factors that moderate the parental effects. Specifically, we examined the effects of childhood and adulthood antisocial behavior of the parents on offspring antisocial behavior as young adults. We also examined whether mothers' and fathers' drinking problems when offspring were young children (6-8 years) affected offspring antisocial behavior as young adults (18-21 years). We evaluated 655 children from 339 families in the Michigan Longitudinal Study (MLS), a prospective study of AUD and non-AUD families. Path models were constructed in order to test for the parental contributions to offspring outcomes. We found that both mothers' and fathers' antisocial behavior contributed to the children's young adult antisocial behavior. Only mothers' drinking problems while their children were little had a significant effect on their sons' later drinking, but not on their daughters'. These different parental effects suggest that maternal and paternal influences may be mediated by different mechanisms. 10.1371/journal.pone.0177288
    Exposure to paternal alcoholism does not predict development of alcohol-use disorders in offspring: evidence from an offspring-of-twins study. Duncan Alexis E,Scherrer Jeffrey,Fu Qiang,Bucholz Kathleen Keenan,Heath Andrew C,True William R,Haber Jon R,Howell Donelle,Jacob Theodore Journal of studies on alcohol OBJECTIVE:Using an offspring-of-twins design, we tested the hypothesis that exposure to paternal alcoholism during the child's first 12 years will increase offspring risk for subsequent alcohol-use disorders (AUD). METHOD:Structured psychiatric interviews assessed history of psychiatric and substance-use disorders in Vietnam Era Twin Registry fathers (n = 512), their offspring (n = 877), and mothers of the offspring (n = 507). Exposure was defined as the fathers' endorsement of any Diagnostic and Statistical Manual of Mental Disorders (DSM), Fourth Edition, AUD symptom, according to the Lifetime Drinking History assessment (administered in 1999), at any time between off- spring ages 0-12 years; all fathers had satisfied DSM, Third Edition, Revised (DSM-III-R), criteria for alcohol dependence in a 1992 diagnostic interview. Cox proportional hazards models were fit to predict time to first symptom of abuse/dependence in offspring. RESULTS:Off- spring exposed to paternal alcoholism were significantly more likely to develop an AUD when compared with offspring of nonalcoholic fathers (hazard ratio [HR] = 1.51; 95% confidence interval [CI]: 1.10-2.07). Although offspring unexposed to paternal alcoholism did not significantly differ from control offspring (HR = 1.50, 95% CI: 0.93-2.41), the magnitude of association was similar to that in the exposed offspring. There were no significant differences in AUD between offspring of alcoholics who were exposed and those who were not exposed to paternal alcoholism, as long as fathers had satisfied DSM-III-R criteria for alcohol dependence at some point in their lives. CONCLUSIONS:There does not appear to be a relationship between exposure to paternal alcoholism during childhood and development of an AUD in offspring. Genetic and high-risk environmental factors that are correlated with lifetime paternal alcoholism may be stronger predictors of offspring AUD than fathers' problem drinking. Future research should be encouraged, using more comprehensive analyses, to examine the role of family genetic influences and other family environmental influences on offspring alcohol outcomes.
    Offspring of male rats exposed to binge alcohol exhibit heightened ethanol intake at infancy and alterations in T-maze performance. Hollander Jessica,McNivens Megan,Pautassi Ricardo M,Nizhnikov Michael E Alcohol (Fayetteville, N.Y.) Alcohol use is associated with a variety of negative consequences, including heightened likelihood of cognitive impairment, proclivity to alcohol use disorders (AUD), and alterations in the drinker's offspring. Children and rodents exposed to alcohol during pregnancy, or those whose fathers consumed alcohol prior to mating, often exhibit neurodevelopmental, physiological, and behavioral deficits. The present study assessed cognitive function and alcohol intake in male and female rats that were offspring of alcohol-exposed fathers. Adult male rats were exposed to alcohol or vehicle (0.0 or 2.0 g/kg, respectively; twice daily for 2 days followed by a rest day, for a total of eight alcohol or vehicle exposure days), or were left untreated and then mated with non-manipulated females. The offspring were assessed for alcohol intake, via intraoral infusion, followed by cognitive assessment via an alternating T-maze task. The results indicated that paternal ethanol exposure, prior to breeding, resulted in offspring that consumed significantly more ethanol than vehicle or untreated controls. Furthermore, the offspring of alcohol-exposed fathers exhibited a significant failure to initiate and complete the T-maze performance tests. Although, when they did engage in the tests they performed at the level of controls (i.e., 80% correct). The present results add to a growing body of literature suggesting that paternal pre-conception alcohol exposure can have deleterious effects on the offspring. 10.1016/j.alcohol.2018.07.013
    The clinical features of alcohol use disorders in biological and step-fathers that predict risk for alcohol use disorders in offspring. Kendler Kenneth S,Ohlsson Henrik,Edwards Alexis,Sundquist Jan,Sundquist Kristina American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics Given that Alcohol Use Disorder (AUD) is clinically heterogeneous, can we, in a large epidemiological sample using public registries, identify clinical features of AUD cases in biological and step-fathers that index, respectively, genetic and familial-environmental risk for AUD in their offspring? From all father-offspring pairs where the father had AUD and the offspring was born 1960-1990, we identified not-lived-with (NLW) biological fathers (n = 38,376) and step-father pairs (n = 9,711). The relationship between clinical and historical features of the father's AUD and risk for AUD in offspring was assessed by linear hazard regression. Age at first registration for AUD and recurrence of AUD registration were significantly stronger predictors of risk for AUD in the offspring of NLW fathers than in step-fathers. By contrast, number of AUD registrations in NLW fathers and step-fathers were equally predictive of risk for AUD in offspring. However, while the number of step-father AUD registrations that occurred when he was living them with significantly predicted risk for AUD in his step-children, the number of registrations that occurred when not residing with his step-children was unassociated with their AUD risk. In an epidemiological sample, we could meaningfully differentiate between features of AUD in fathers that indexed genetic risk which was transmitted to biological offspring (early age at onset and recurrence) versus indexed environmental risk (registrations while rearing) which increased risk in step-children. 10.1002/ajmg.b.32583