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Essay on Physiological Psychology: The Symptoms and Causes of Phenylketonuria, Galactosemia and Tay-Sachs Disease

The development of genetics revealed a lot of interesting facts about functioning of human organism. Probably one of the most important discoveries that have been made is the discovery of the fact that certain diseases and disorders may be genetic by their character. Among such diseases may be named phenylketonuria, galactosemia, and Tay-Sachs disease. All of them are genetic disorders, which are to a certain extent interrelated.

Speaking about phenylketonuria, it is necessary to point out that it is a human genetic disorder in which “the body lacks phenilalanine hydroxylase, the enzyme necessary to metabolise phenylalanine to tyrosine”. Obviously, it is a very serious disease which needs urgent treatment, otherwise the consequences may very dangerous for human organism. Actually, the disease can result in brain damage and progressive mental retardation. These negative consequences may be the result of accumulation of phenylalanine and its breakdown products. The disease may be detected with the help of analysis of a small blood sample.

Another genetic disorder is galactosemia, which is a rare disease that affects an individual’s ability to proper digest the sugar galactose. Basically, lactose in food is broken down by the body into glucose and galactose. In a healthy organism, galactose is then converted into glucose by the enzyme GALT. The disease progresses in the result of the process, when GALT activity is severely diminished, “leading to toxic levels of galactose to build up in the blood, resulting in hepatomegaly (an enlarged liver), renal failure, cataracts, and brain damage”. Obviously, the consequences of the disease are extremely dangerous and the progress of the disease may lead to death. It is particularly dangerous at early age. In this respect it worth to note that mortality in infants with galactosemia is about 75%. Moreover, there are several factors that are responsible for the severity of the disease, among which may be named the amount of lactose in the diet of an individual, and some others.

Another disease, Tay-Sachs disease, is closely related to gene disorders and which is also extremely dangerous for human brains and organism at large. Moreover, this disease is often fatal, especially in its most common variant known as Infantile Tay-Sachs disease. Basically, it is inherited in an autosomal recessive pattern. As a rule the disease occurs when “harmful quantities of a fatty acid derivatives called a ganglioside accumulate in the nerve cells in the brain” (). The recent researches revealed the fact that Tay-Sachs disease caused by mutations on the HEXA gene on chromosome 15. It is noteworthy that most HEXA mutations are rare or even do not occur in genetically isolated populations. Basically, the disease can potentially occur from inherited two unrelated mutations in the HEXA gene, one from each parent.

Thus, in conclusion, it is possible to say that the three diseases discussed above indicate at the great role genes can play in the development and life of human organism. At the same time, this fact indicates at the necessity of the development of genetic researches in order to provide the possibility not simply to find the cause of a disease but also prevent it effectively.


1. Carlson, N. Foundations of Physiological Psychology. New York: Routledge, 2005.
2. Moe, MD, et al.. “Neurologic & Muscular Disorders”, Current Pediatric Diagnosis & Treatment, 17th, 2005. Can Write an Essay on Physiological Psychology for You!

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