Genomics When one suggests that a behavior is determined genetically, then one horribly oversimplifies the situation, and negates the importance of culture and free will in determining how a person behaves. One behavior that has gained large-scale acceptance as having a partial genetic cause is that of alcoholism. This genetic cause I expressed in terms of risk factor. It has often been noted that the children of alcoholics are more at risk of becoming addicted to alcohol than are other children. in the last five or so years, technique arising from the Human Genome Project have made it possible to sequence human genes and actually try to pinpoint the locus of the genes associated with alcohol risk.
One of the studies examined in this paper even goes so far as to suggest that the gene that is associated with alcoholism determines not only one’s risk for alcohol, but even the alcohol consumption habits of social drinkers. This is significant because it suggests that even normal behavior is genetically determined. Some studies of alcohol addiction correlate the risk for addiction with social disorders in general, which can be seen from childhood. It is one of the points of this paper that such correlations do not represent a genetic predisposition to antisocial behavior, but rather a potential cause for alcoholism which is not necessarily genetic. Data: 1) The first study examines beta-endorphin (An endorphin produced by the pituitary gland that is a potent pain suppressant) responses to alcohol among monozygotic (MZ, of or from one fertilized egg, as identical twins) and dizygotic (DZ, developing from two fertilized eggs, as fraternal twins) twins.
The study was conducted at the University of Indiana, and the subjects were 51 MZ and 37 same sex DZ twins. The hypothesis was that beta-endorphin levels as a response to alcohol consumption are determined by genetic factors. Also, it is hypothesized in this study that a higher level of beta-endorphins in the blood as a response to consumption of ethanol is an indicator of heightened risk of alcoholism. The study suggests that because beta-endorphins produce many of the feelings associated with alcohol intoxication (relaxation, euphoria, etc.), those who produce more beta-endorphins after consuming alcohol are at higher risk of becoming alcoholic. 2) The next study involved catechol-0methyltransferase (COMT), which is an enzyme involved in dopamine metabolism. Previous studies have shown that the gene for this protein is associated with alcoholism. The results of previous studies have suggested that enzyme is involved not only in alcoholism, but also social drinking.
The results of the statistical analysis showed that in each of the three genotypes for COMT, there was no difference in distribution of age and other background. There were also no differences in frequency of alcoholism risk indicators between the different groups. Because none of the participants in the study were alcoholics or abstainers, all the subjects were assumed to be social drinkers. What the finding, then, suggests, is that COMT genotype is a significant factor in the patterns of social drinkers. 3) The third study deals with the populations of various Asian groups in which polymorphism in both the alcohol dehydrogenase-2 (ALDH2) and low Km aldehyde dehydrogenase (ALDH2) genes are prevalent.
Certain variations of these genes result in the inability to properly process alcohol, causing a buildup of hemoglobin-associated acetaldehyde (HbAA). This causes discomfort and tissue damage, and has been hypothesized as an indicator of alcoholism in that those with the atypical gene tend not to consume much alcohol. This study confirms the findings of earlier studies that the atypical form of the ALDH2 does indeed result in the inability to fully process alcohol, and therefore results in the buildup of HbAA. 4) The fourth study also deals with the supposed lack of alcohol tolerance among some members of Asian communities. This study deals with the alcohol dehydrogenase genes (ADH2 and ADH3) that act on alcohol metabolism with different levels of efficiency.
Those with certain genotypes process alcohol less efficiently and therefore experience discomfort upon alcohol consumption. 5) The fifth study , titled “Fetal Associative Learning Mediated through Maternal Alcohol Intoxication”, deals with the reactions of rats to alcohol administered prenatally. The study consisted of administering alcohol along with an odoriferous substance to pregnant rats in order to see if the baby rat forms an association between alcohol and the odorous substance prenatally, which can be observed in the postnatal behavior. The result was that the rats that were administered alcohol and cineole (oil of wormwood) reacted differently to cineole that did the rats that were given just cineole, just alcohol, or nothing. This indicates that the rats formed an association between the two substances before birth. This observed association postnatally from prenatal stimuli indicates that prenatal learning based on alcohol is possible in rats.
6) The sixth study deals not specifically with genetics, but with behavioral dysfunction in childhood and adulthood, and its relationship to alcoholism. The study was conducted upon some 102 prisoners of a Japanese prison. The subjects were statistically examined based on their family history of alcoholism and antisocial personality disorder (ASP). Further comparisons of the information were used to determi8ne which characteristics were related to which. It was found that those prisoners which records of severe childhood conduct disorder had a much higher probability of becoming alcoholic and at an earlier time in life than those who didn’t have such a history. Subjects who had a history of childhood conduct disorder were also shown to be more likely to have been arrested for violence while intoxicated that those who had no childhood history, or whose family history included alcoholism but not ASP. This study suggests that behaviors surrounding alcohol consumption are influenced by factors other than simple familial risk.
Behavioral disorders, whatever causes them, seem to have as much to do with the expression of alcohol dependence as does family history. 7) The seventh and final study examined deals with the association between parental history of alcoholism and behavioral problems in Native American children from Southern California. The study was conducted upon 96 children from various Southern California reservations. The information for the study was gathered through a questionnaire that was filled out usually by the mother, which asked her to list the relatives who displayed significant alcohol related problems. This data was then analyzed along gender, age, and family history lines, to determine the various effects of family history of alcohol problems on the behavior of children.
The results of the analysis were different for boys and girls. Among boys it was found that familial history had no influence over the age at which behavioral problems were observed. However, males with alcoholic relatives did prove to be more prone to behavioral problems of both internal and external nature, without regards to age of expression. The statistics on familial alcoholism as it relates to behavioral problems in children and adolescents is consistent with that for other ethnicities. Discussion: The first study claims in its introduction that genetic factors account for at least 40% of the risk of alcoholism.
This kind of statistic should always be viewed with skepticism because there are too many variables. This study suggests that differences in risk of alcoholism are caused by the differences in beta-endorphin response. This claim is made because beta-endorphins produce many of the same effects attributed to alcohol. That is, they produce feelings of well being, relaxation and euphoria. The authors of the study hypothesize that because people genetically respond differently to alcohol consumption, those that produce more beta-endorphins are more likely to become addicted.
There are a couple of problems with this study, however. The hypothesis is, after all, only a hypothesis. There was no background check done to see if those twins that responded with a greater than average beta-endorphin response were in fact at a higher risk of alcohol addiction based on family history. Another interesting aspect of this study is that DZ twins usually reacted differently from one another in te4rms of beta-endorphin response. This does indeed seem to illustrate that the reaction to alcohol is heritable, because MZ twins react the same.
This demonstrates something further though. It s …