Inherited Tendencies in Alcoholics
Alcoholism designates a chronic and progressive disorder characterized by the inability to control the consumption of alcohol.
Alcoholism is sometimes also referred to as alcohol use disorder (AUD). It may lead to death due to the internal consequences of long-term alcohol abuse, which include cirrhosis of the liver, cardiac arrest and cancers of the liver, pancreas, lung, colon and rectum.
Alcoholism is most likely a multifactorial disorder caused by the action of several genes in concert with environmental influence.
Inherited tendencies that may play a role include how an individual metabolizes alcohol, an individual’s hormonal and behavioral response to alcohol, and his or her tolerance for levels of alcohol in the blood.
Biochemically, those prone to alcoholism may experience more pleasurable effects than others. (A preference for alcohol can be selectively bred into experimental animals).
A familial link has been recognized in alcoholism since ancient times, and numerous studies have found increased risks for the disorder among relatives of those affected.
Estimates in the percentage of the general population that will develop alcoholism generally range from 3% to 10% of males and 1% to 3% of females. (Estimates of the number of alcoholics in the United States are generally put at approximately 10 million.)
Sons and brothers of alcoholic males may have three to five times this risk, and daughters of female alcoholics three times.
In identical (monozygotic) twins Opens in new window there is a concordance (both display the trait) of more than 50%, while the concordance is less than 30% for fraternal (dizygotic) twins Opens in new window of the same sex. Familial alcoholism Opens in new window tends to develop early in life.
Studies of adoptees indicate that heredity plays a stronger role than environment in producing alcoholics, with the rates among adopted children of male alcoholics more reflective of the risks associated with their biological than their adoptive fathers. Also, sons of alcoholics who are themselves not alcoholics have a higher tolerance for alcohol than sons of non-alcoholics.
Some ethnic groups show an increased incidene of alcoholism and some a markedly decreased tolerance for alcohol.
Native Americans and individuals of Irish descent are among the former group, while Asians are among the latter.
Many Asians lack an enzyme responsible for breaking down acetaldehyde, a toxic stimulant that is a byproduct of alcohol metabolism.
Individuals with this enzyme deficiency become flushed, dizzy and experience headaches and nausea after ingestion of small amounts of alcohol. An estimated two-thirds of Asians exhibit ill effects from alcohol, while only about 5% of whites are similarly affected.
A small molecule, alcohol is easily absorbed throughout the body, and, in pregnant women, can enter the fetal blood via the placenta. The developmental anomalies that may occur as a result are termed fetal alcohol syndrome.
- Adapted from The Encyclopedia of Genetic Disorders and Birth Defects By James Wynbrandt, Mark D. Ludman