Alcohol Report{{vm.user.Username}} - {{vm.user.Age}}yo {{vm.user.Gender === 'M' ? 'male' : 'female'}}

Alcohol is metabolised into a toxic and carcinogenic substance called acetaldehyde which is then converted to harmless acetate. The first step is controlled by the ADH1B enzyme and the second by ALDH2 enzyme.

The ADH1B (rs1229984) SNP changes the enzyme structure and increases its ability to convert alcohol to acetaldehyde. This leads to the accumulation of acetaldehyde in the blood.

The ALDH2 (rs671) SNP produces an inactive enzyme with a reduced ability to clear acetaldehyde from the body. Individuals with the ALDH2 variant SNP have a reduced risk of alcoholism and will develop hangover symptoms from a smaller amount of alcohol. In some genotypes, the risk of adverse health outcomes such as oesophageal cancer increases with alcohol consumption.

Evidence Rating for Risk

Predicted Outcome

{{vm.outcome}} sensitivity to alcohol

Genotype

ADH1B {{vm.details.Genes.ADH1B | alleles : '/' }}
ALDH2 {{vm.details.Genes.ALDH2 | alleles : '/' }}

Phenotype

Interpretation

Recommendations

Notes

Light drinkers are people who consume 1 or less standard drinks per day while heavy drinkers are people who consume 5 or more standard drinks per day (400g of alcohol per week).
1 standard drink contains 10 g of alcohol
The risk for cancers will vary depending on the ethnic group.
In the East Asian population cancer of the oesophagus is very common and there are several studies describing the risk of this cancer in each of the test result groups. In the Caucasian population, cancer of the oesophagus is rare and the studies only provide risks for head and neck or upper gastrointestinal cancer.
The ALDH2 genetic change does not appear to occur in the Caucasian population but does occur in various Asian populations. The highest frequency of the ALDH2 genetic change is in the Han Chinese population.
All risk figures are derived from a comparison with the genetic finding that has the least cancer risk, not a comparison to a non-drinking group. This means the absolute risk may be significantly greater than quoted above. For example, risks for oesophageal cancer as high as 30-70 times have been reported in alcohol drinkers when compared with non-drinkers ¹.

References

1. Zhang GH, Mai RQ, Huang B. Meta-analysis of ADH1B and ALDH2 polymorphisms and esophageal cancer risk in China. World J Gastroenterol 2010; 16(47): 6020-5.

2. Yokoyama M, Yokoyama A, Yokoyama T, et al. Hangover susceptibility in relation to aldehyde dehydrogenase-2 genotype, alcohol flushing, and mean corpuscular volume in Japanese workers. Alcoholism, clinical and experimental research 2005; 29(7): 1165-71.

3. Chen CC, Lu RB, Chen YC, et al. Interaction between the functional polymorphisms of the alcohol-metabolism genes in protection against alcoholism. Am J Hum Genet 1999; 65(3): 795-807.

4. Guo H, Zhang G, Mai R. Alcohol dehydrogenase-1B Arg47His polymorphism and upper aerodigestive tract cancer risk: a meta-analysis including 24,252 subjects. Alcoholism, clinical and experimental research 2012; 36(2): 272-8.

5. Chuang SC, Agudo A, Ahrens W, et al. Sequence Variants and the Risk of Head and Neck Cancer: Pooled Analysis in the INHANCE Consortium. Front Oncol 2011; 1: 13.

6. Zhang G, Mai R, Huang B. ADH1B Arg47His polymorphism is associated with esophageal cancer risk in high-incidence Asian population: evidence from a meta-analysis. PLoS One 2010; 5(10): e13679.

Evidence Rating System

We have developed a ratings system so that you can see our level of confidence in the research that we have used as a basis for our recommendations. This is based on Oxford Centre for Evidence Based Medicine – Level of Evidence, March 2009* and has been modified by myDNA to apply for genetic tests.

Level	Causation and treatment
★★★★★	Systematic review of multiple RCT (meta-analysis) Systematic review of meta-analyses Single RCT (randomised controlled trial) with narrow confidence intervals
★★★★	Meta-analysis of cohort studies Prospective cohort with 80% follow up Single RCT not in 5 Good quality ecological research Genome-wide association studies
★★★	Multiple case control studies Meta-analysis of case control Follow up cohort <80% Cross sectional studies >1000 people Case control good quality
★★	Single case control not in 3 Case-series Cross sectional <1000 people
★	Single case report Expert opinion Biochemistry First principle Animal/bacteria analogy

*http://www.cebm.net/oxford-centre-evidence-based-medicine-levels-evidence-march-2009/