engleski

Genetics and alcoholism: An example ofmultiple interactions of a crug and heredity

Both substances of abuse and numerous drugs used in psychiatry and neurology alter the function of human brain. There is no clear border between them, and even the cechanisms of their action are identical or very similar. The mesolimbic dopamine system, an anatomical and neurochemical substrate of the so-called rewarding center, seems to play a key role in the occurrence of drug dependency. In knockout mice, for example, lacking the D2 dompaine receptor, opiates do not produce any rewarding effect. Investigations in drug dependent patients, and the findings are most convincing in alcoholics, clearly stress the genetic differences form the rest of the population. For example, the A1 allele of the D2 receptor gene is found in about 70% of severe alcoholics and in only 20% of the rest of the population. The difference betrween the genes (A1 and A2 alleles) is localized in their regulatory parts, so alcoholics, consequently, as determined by means of PET scanning, have fewer D2 brian receptors. This is an example of a 'dependence-promoting' inheritance, but there are opposite examples, as well. The japanese, and some other nations of the Far East, frequently have the ALDH2(2) allele that encodes for a poorly active aldehyde dehydrogenase. Consequently, they experience very unpleasant symptoms after ingestion of even very small amounts of alcohol. The population genetic studies show that the ALDH2(2) homozygotes practically never become alcoholics.

alcohol; gene polymorphism; D2 receptor

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