In the to come genetic information may be a valuable tool for the diagnosis of alcoholism.

In the to come genetic information may be a valuable tool for the diagnosis of alcoholism. At quick in emergencies the specific genes involved remain to be identified, and the compass to which environmental factors contribute is not clearly understood.

Gene have extended been suspected to play a part in the etiology of alcoholism. Genetic influences first were indicateed in family studies demonstrating that the incidence of alcoholism among relatives of alcoholics is several times higher than that observ among relatives of nonalcoholics (Cotton 1979) Since then, genetic influences have been confirmed in studies of adopted children whose biological parents were alcoholic and in studies of twins (Schuckit et al. 1985)

Adoption studies have build the incidence of alcoholism among biological children of alcoholics to be several times higher than that construct among biological children of nonalcoholics, uniform when both groups of children were separated from their parents early in life and raised at nonalcoholic adoptive parents (Goodwin et al. 1973; Cloninger et al. 1981)

Twin studies have compared agreement (concordance) for the expression of alcoholism between pairs of monozygotic (identical) and dizygotic (fraternal) twins. Because monozygotic (MZ) twins are genetically identical, while dizygotic (DZ) twins are no more genetically alike than are nontwin siblings, the expectation is that a trait with a genetic composing is more likely to be concordant in a sample of MZ twins than in a sample of DZ twins. In general, twin studies have set up greater concordance for alcoholism among monozygotic twins than among dizygotic twins (Kaij 1960; Pickens et al. 1991)

Can the knowledge that genetic influences contribute to alcoholism play a useful part in the diagnosis, prevention, and treatment of this disorder? Undoubtedly, undivided day it will, but at at hand this knowledge is too limited to be of practical use. This article reviews now passing limitations that prevent the use of genetic information for diagnosing alcoholism or a predisposition to alcoholism. The article also examines environmental influences that bewilder interpretations of a genetic influence and make it impossible to determine the expanse to which genetic influences are involved. Finally, the article reviews novel findings that suggest genetic influences may explain an of the variation seen in the expression of alcoholism, and glance ats directions for future research.

LIMITATIONS OF GENETIC KNOWLEDGE

Genetic testing popularly cannot be used to predict or diagnose alcoholism for sum of two units major reasons. First, research characterizing genetic factors involved in alcoholism is at an early stage. Although genetic influences are known to contribute to the disorder, the specific gene (or, more correctly, the alternative gene forms, or alleles) involved have not been identified. In the human genome, there are an estimated 100000 gene of which 20000 are believed to be uttered in the central nervous classification (Sutcliffe 1988). An unknown number of gene have alleles that may be involved in alcoholism. latter findings in humans suggest that alcoholism may be becoming to a major genetic efficiency involving a number of gene located at sum of two units or more chromosomal locations, or loci (Aston and Hill 1990) Animal studies indicate that loci on at least 10 different chromosome may contain alcohol-relevant gene (McClearn et al. 1991) further until the specific genes are identified, we cannot determine who carries them.

secondary even if the relevant alleles were known, genetic influences alone are not likely to determine whether alcoholism will evolve A number of environmental influences also have been associated with alcohol use and with alcoholism (Zucker and Gomberg 1986) single in kind important, but often overlooked, environmental influence is the physical availability of alcohol. equal an individual possessing all the necessary gene for alcoholism will not evolve the disorder if alcohol is not available or if that individual not drinks. Although no data exist to indicate that reducing alcohol availability affects the incidence of alcoholism, public policies restricting the availability of alcohol have been shown to make less per capita consumption and alcohol-related death and disease (Rush et al. 1986)

Another important environmental influence forward the development of alcoholism is alcohol itself. A number of studies have shown that alcohol can act as a primary biological reinforcer, that is, its intoxicating, anxiolytic, and other validitys may reinforce continued alcohol consumption (see Lewis and Lockmuller 1990) Alcohol's reinforcing weights may contribute to alcohol- seeking behavior and ultimately to alcoholism in humans.

Alcohol-seeking behavior has been demonstrated in a variety of animal designs (Meisch 1976, 1977). Animals of diverse genetic backgrounds have been shown to self-administer alcohol, either by means of pressing a lever that delivers alcohol intravenously or by means of drinking alcohol solutions in estimation to water (Winger and copses 1973). In similar studies, animals have been shown to address a location in which an alcohol injection was received above a location in which a placebo injection was received (Reid et al. 1985) Given that there is high correspondence between various remedys that will be self- administered at animals and those used on humans (Johnson 1990). these findings hint that alcohol may act as a reinforcer in humans as well. Thus, it appears theoretically possible for someone to become an alcoholic simply as a be the effect of drinking alcohol, in the absence of specific genetic influences.