Rutgers Researchers Delve Deep Into the Genetics of Addiction

For example, this study from 2013 makes a strong case for genetic predisposition. Learn more about hereditary alcoholism, including the latest research on genetic variants, from the Delphi Behavioral Health Group. Another genetic factor for alcoholism may be an association of a variant of the DRD2 gene, which affects the neurotransmitter dopamine. The brain releases dopamine in greater quantities when drinking and lifts the mood, activating the brain’s reward system.

  • The material is not a substitute for qualified medical diagnoses, treatment, or advice.
  • Mental illnesses, such as depression and schizophrenia, are more common in people with a family history of these disorders.
  • Gene × environment interaction (G × E) occurs when the effect of exposure to an environmental factor on a person’s health is conditional upon his or her genotype (for review see Caspi & Moffitt [68]).

The identified genes were functionally classified as oncogenes/tumour suppressors, ion channel/transport proteins, transcription factors and ubiquitination related. Murphy et al. (2002) reported that only two genes differed between C57BL/6J and BALB/c (c-FMS and cyclin A1). However, other changes in expression were observed, but the differences were small and could not be confirmed by reverse transcription PCR. It should be noted that these early studies utilized different array platforms that contained a relatively small number of features per array. Also, the study designs did not allow a formal statistical analysis; thus, gene selection was based on arbitrary cut-off ratios or qualitative interpretation.

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Abundant evidence indicates that alcoholism is a complex genetic disease, with variations in a large number of genes affecting risk. Some of these genes have been identified, including two genes of alcohol metabolism, ADH1B and ALDH2, that have the strongest known affects on risk for alcoholism. While the answer is not cut-and-dry, those with alcoholic parents show an increased risk of alcohol use disorders and developing an addiction to alcohol. Research shows that there is a hereditary factor in the development of alcohol use disorders (AUDs).

  • Early expression profiling studies examined inbred long-sleep and short-sleep mice (Xu et al., 2001), and several inbred strains of mice (C57BL/6J, BALB/c, A/J and DBA/2J) that differ in voluntary ethanol consumption (Murphy et al., 2002).
  • In some people, a variant with reduced activity is present, resulting in more severe symptoms of intoxication.
  • Disease can be woven into your DNA — and that includes the disease of drug addiction.

That said, almost every study concluded that genetics are not the sole factor in alcoholism. Instead, it’s a combination of alcoholism, environmental factors, and the frequency of alcohol consumption. According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), a person’s genetic makeup accounts for roughly half of their risk for developing an AUD. The studies outlined in this section demonstrate that large data sets of gene expression data can be combined with behavioural and genetic data to identify genes or functional pathways that underlie ethanol-related phenotypes and other complex traits. Although most of the genetic determinants of alcoholism remain to be discovered there are reasons for optimism. In recent years a technological revolution has occurred producing a shift from single-locus studies to genome-wide searches.

Am I at Risk of Becoming Addicted to Alcohol?

Individuals were genotyped using Illumina Human610Quad or Illumina Human660w Quad BeadChips (Illumina Inc). When patients reduce or abruptly stop heavy drinking they may experience a withdrawal syndrome. Withdrawal symptoms include nausea, nervousness, sleep disturbances, the strong urge to drink (“binge drinking”), irritability, and depression. If the patient already has advanced physical dependence they may also experience heavy sweating, trembling (especially of the hands), flu-like symptoms, and – in extremely bad cases – seizures with tongue biting and hallucinations. Worldwide, the ratio of men to women who drink alcohol is 3.8, with 54% of men and 32% of women reporting being drinkers. According to the World Health Organization, worldwide drinking patterns vary across countries.

  • As a technical definition, genes are a sequence of nucleotides that make up parts of a chromosome.
  • Researchers are discovering other gene variants that also point toward a greater likelihood of alcohol abuse or alcoholism.
  • On the other hand, people who can tolerate comparatively large amounts of alcohol are at risk of becoming dependent in the long term, suggesting a genetic predisposition.
  • Sufferers can be unaware of the severity of their illness and may deny it altogether.
  • In the future, there may be genetic therapies that help people control how much alcohol they consume; for now, behavioral therapies have proven very effective at managing these chronic health conditions.

The more lines of evidence for a gene—that is, the more times a gene shows up as a positive finding across independent studies, platforms, methodologies and species—the higher its external CFG score (Figure 1). This is similar conceptually to the Google PageRank algorithm, in which the more links to a page, the higher it comes up on the search prioritization list. It has not escaped our attention that other ways of weighing the lines of evidence may give slightly different results in terms of prioritization, if not in terms of the list of genes per se.

Alcohol Abuse Is Influenced by Environmental and Genetic Factors

Thus, the
genes and SNPs found through GWAS have had little overlap with previous findings
based on candidate genes/pathways and linkage analyses. Alcoholism occurs due to individual choice, environmental and genetic determinants and interactions between factors within these three domains of causation (Fig. 2). Environmental factors include alcohol availability, parental attitudes, peer pressure, underage drinking and childhood maltreatment. From this perspective the ability to detect gene effects is dependent upon context and timing [65]. Severe childhood stress and neglect increase vulnerability to alcoholism but also several alcoholism-related psychiatric diseases including ASPD, CD, anxiety and depression, with the risks of these common diseases being elevated several-fold in the stress-exposed [66,67].

  • The GWAS study (cohort 1) on which our discovery was based contained males as probands but contained males and females as controls.
  • In addition, concomitant smoking has been shown to alter gene expression in the prefrontal cortex and ventral tegmental area of human alcoholics (Flatscher-Bader and Wilce, 2006; Flatscher-Bader et al., 2008).
  • The current literature finds no consistent evidence that receiving information about genetic risk for things like cancer inspires people to change their behavior.
  • A 2018 study also showed that genetic factors account for 40 to 60 percent of the reasons people develop AUD.14 Since that study, specific genes have been identified that link with the development of the disorder.
  • Environmental factors include alcohol availability, parental attitudes, peer pressure, underage drinking and childhood maltreatment.

Looking at adoptees, for example, if their biological parents were alcoholics, they may be more likely to abuse alcohol, but it’s not a given. Lab rats and mice bred to choose alcohol and bred to have a more painful withdrawal to intoxicants reinforce the idea that alcoholic traits are rooted in genetics. Research shows genes contribute to approximately half the risk of developing alcohol use disorder. Genome-wide scans, including whole genome linkage and whole genome association (WGA), allow the hypothesis-free mapping of disease-causing loci within the genome. Chromosome regions and genes implicated by these studies, as well as potential strengths and limitations of WGA methodologies, are discussed below. Children of addicted parents are more likely to become addicted than other children.

Is Alcoholism Hereditary? A Detailed Look at Alcohol Genetics

Nominally significant interactions were found between SNPs in SNCA and RXRG, DRD2 and SYT1, MOBP and TIMP2. The corresponding genes merit future follow-up work to elucidate the biological and pathophysiological relevance of their interactions. The test cohort 2 data were used to test for epistatic interactions among the best P-value SNPs in the 11 top candidate genes from our work. SNP–SNP allelic epistasis was tested for each distinct pair of SNPs between genes, using the PLINK software package (Supplementary Table S5). Research on addiction science, prevention, and treatment are a large focus of the National Institute on Drug Abuse, which provides funding to support research. This condition has been present in human history since men learned to ferment fruit – which is about 10 million years ago.

what percentage of alcoholism is genetic

The incidence of alcoholism was slightly higher among people who were exposed to alcoholism only through their adoptive families. However, it was dramatically higher among the twins whose biological fathers were alcoholics, regardless of the presence of alcoholism in their adoptive families. If addiction is part of your family’s health history, you’re more prone to develop a substance use disorder. About half of your susceptibility to developing a substance use disorder (SUD) can be hereditary.

A number of studies have focussed on the identification of quality control guidelines that should be considered when performing expression profiling of human post-mortem brain (Tomita et al., 2004; Jackson et al., 2005; Atz et al., 2007). For example, post-mortem interval, agonal state and pH are all important variables that affect transcript quality. In addition, psychiatric disorders such as schizophrenia (Mirnics et al., 2000, 2001; Pongrac et al., 2004), major depression (Evans et al., 2004), bipolar disorder (Iwamoto et al., 2004b) and autism (Purcell et al., 2001) have been studied successfully. The results of these studies indicate that the levels of numerous genes are altered and identification of such changes using the ‘single target’ approach would be inefficient. Each of these endophenotypes is likely to reflect the actions of multiple genes and to relate to both genetic and environmental influences (Schuckit et al., 2004b; Crabbe et al., 2006).

For studies of rare variants, families are quite valuable for sorting
out true positives from the background of individual variations that we all
harbor. Alcohol tolerance means that equal amounts of alcohol lead to lesser effects over time, generating a need for higher quantities of alcohol to feel the same desired effects.2 While is alcoholism inherited it may seem like there is a genetic predisposition for alcohol tolerance, tolerance is not inherited. People who have a different variant of the gene quickly burn up the alcohol, which in turn spikes their acetaldehyde levels, leading to hangovers. Perhaps this condition could be considered a genetic predisposition to alcoholism.

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