Ebrii gignunt ebrios--One drunkard begets another: the genetics of alcohol dependence

Pattern of Risks for Psychiatric and Substance Use Disorders in the Offspring of Parents With Alcohol Use Disorder

OBJECTIVE

The authors sought to clarify the components of the familial liability to alcohol use disorder (AUD) by examining parent-offspring transmission in a large Swedish population sample.

METHODS

To this end, 1,244,516 offspring in intact families with a mean age at follow-up of 37.7 years (SD=6.8) were examined. Hazard ratios for offspring of parents with AUD were calculated using Cox models for risk of five disorders assessed from Swedish medical and criminal registries: AUD, drug use disorders, attention deficit hyperactivity disorder, major depression, and anxiety disorders.

RESULTS

The hazard ratio for the offspring was highest for AUD (hazard ratio=2.36), followed by drug use disorder (hazard ratio=2.04), attention deficit hyperactivity disorder (hazard ratio=1.82), major depression (hazard ratio=1.43), and anxiety disorder (hazard ratio=1.43). The risks for AUD were statistically indistinguishable between the children having mothers with AUD compared with those having fathers with AUD and between sons and daughters of a parent with AUD. All risks for offspring having two parents with AUD were higher than those having one parent with AUD, but the increase with two parents with AUD was greatest for AUD, followed by drug use disorder and attention deficit hyperactivity disorder. Age at AUD onset of the parents predicted risk among the offspring more strongly for AUD and drug use disorder, followed by attention deficit hyperactivity disorder, and then major depression and anxiety disorders. Number of recurrences of the parents with AUD predicted risks for all disorders equally. The risk pattern of disorders for the offspring of not-lived-with fathers with AUD was similar to that in the main analysis of intact families. No evidence was found for sex-specific transmission of AUD or a familial female protective effect.

CONCLUSIONS

Familial and likely genetic liability to AUD has three components: a nonspecific risk of common internalizing and externalizing disorders, a moderately specific risk of externalizing disorders, and a highly specific risk of AUD.

Confirmation of prior evidence of genetic susceptibility to alcoholism in a genome-wide association study of comorbid alcoholism and bipolar disorder

OBJECTIVES

Alcoholism and affective disorders are both strongly comorbid and heritable. We have investigated the genetic comorbidity between bipolar affective disorder and alcoholism.

METHODS

A genome-wide allelic association study of 506 patients from the University College London bipolar disorder case-control sample and 510 ancestrally matched supernormal controls. One hundred forty-three of the bipolar patients fulfilled the Research Diagnostic Criteria diagnosis of alcoholism. A total of 372 193 single nucleotide polymorphisms (SNPs) were genotyped. Genes previously shown to be associated with alcoholism and addiction phenotypes were then tested for association in the bipolar alcoholic sample using gene-wise permutation tests of all SNPs genotyped within a 50-kb region flanking each gene.

RESULTS

Several central nervous system genes showed significant (P<0.05) gene-wise evidence of association with bipolar alcoholism. The genes implicated, which replicated genes previously shown to be associated with alcoholism were: cadherin 11, collagen type 11 α2, neuromedin U receptor 2, exportin7, and semaphorin-associated protein 5A. The SNPs most strongly implicated in bipolar alcoholism, but, which did not meet conventional genome-wide significance criteria were the insulin-like growth factor-binding protein 7, carboxypeptidase O, cerebellin 2, and the cadherin 12 genes.

CONCLUSION

We have confirmed the role of some genes previously shown to be associated with alcoholism in the comorbid bipolar alcoholism subgroup. In this subgroup, bipolar disorder may lower the threshold for the phenotypic expression of these alcoholism susceptibility genes. We also show that some genes may independently increase susceptibility to affective disorder and alcoholism.

Alcohol and the liver

PURPOSE OF REVIEW

To apprise the reader of advances in 2005 in the epidemiology, pathogenesis, prognosis and treatment of alcoholic liver disease. Alcohol use has declined in developed countries, but the opposite is true elsewhere; alcoholic liver disease is a considerable burden worldwide.

RECENT FINDINGS

Genetic mechanisms for alcoholic liver disease are being discovered in addition to aggravating cofactors, such as hepatitis C, obesity and iron overload, and ameliorating ones, like coffee and tea drinking. The involvement of the innate immune system and the mechanisms of apoptosis in alcoholic liver disease are better appreciated, especially the emerging role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Steroid use and nutrition for alcoholic hepatitis are being refined, and the validity of the model for end-stage liver disease (MELD) score in predicting the outcome of alcoholic liver disease is upheld. Recidivism after liver transplantation for alcoholic liver disease adversely impacts long-term survival.

SUMMARY

Inroads are being made into the genetics of alcoholic liver disease and new phenomena are being uncovered in its pathogenesis, but safe and effective therapies for both alcoholic hepatitis and alcoholic cirrhosis are still wanting.