The incidence of single nucleotide polymorphisms (SNPs) variations of a single "letter" on specific points of the gene has been studied in all the cases. Within the family of metabolic genes the SNPs of the genes ADH1A-ADH1B-ADH1C, ADH4, ADH6, ALDH2 and CYP2E1 have been analysed; "70 % of the alcohol is broken down by enzymes encoded by these genes" points out Celorrio. Of the genes in the dopaminergic system, the SNPs analysed correspond to the genes TH, SLC18A2, DRD1, DRD2, DRD3, MAOA and COMT, "being the ones linked to the entire useful life of the dopamine: its production, delivery, action in the presence of receptors and destruction," adds the author. The incidence of the two families of genes has been analysed in two groups of population samples: 1-excessive consumers and 2-patients with dependence.
Among the excessive consumers, polymorphisms that significantly increase the risk associated with the hazardous intake of this substance were found in the ADH1B and DRD2 genes for both sexes and in the MAOA gene in women only. The analysis of the environmental variables together with the hazardous intake of alcohol displayed a high-risk profile: men, smokers, heavy consumers of meat and low consumers of fruit and vegetables, with occupations not requiring a high level of qualifications and physically not very active.
On the other hand, a significant association of alcohol dependence with polymorphisms in genes of the metabolism and dopaminergic route was observed with an SNP of the ADH1B gene in both sexes and with SNPs of TH, COMT, DRD2 in men only, whereas the association with DRD3 occurred in women alone.
The study of excessive consumers was carried out on a sample of 1,533 individuals (653 cases and 880 controls) originating in the EPIC (European Prospective Investigation into Cancer and Nutrition) project, of wh
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