Galactosemia: A Rare Milk Sugar Disorder
Galactosemia is a rare congenital disorder which affects the body's inability to convert galactose into glucose. Galactose is a type of sugar, which is a breakdown product of lactose. Lactose is found in milk and milk products, including breast milk. Given that the galactose can not be broken down, it builds up in the body and acts as a poison that can cause serious damage to its carrier("galactosemia"). "As milk is important to a baby's diet, early diagnosis is essential to avoid lifelong problems from this potentially fatal disorder "(Chung). This research paper provides information about the genetic part of Galactosemia, the cause, symptoms, diagnosis, treatment.
The first trace of information that was brought to light about galactosemia was in 1908 by Von Ruess. He composed an article of his findings in an infant with many of the symptoms we now relate to galactosemia. This work has widely been accepted by scientists as the first reported case of galactosemia. However, at this time the diagnosis of galactosemia was not yet possible. It would be nine years before a similar diagnosis of galactosuria was largely accepted by scientists as a hereditary disorder.
In 1917, galactosuria was treated by eliminating dairy products from an individual's diet. ("galactosemia") The discovery of galactosemia was published by Manson and Turner in immense detail. Although this disease was recognized earlier, it was not until 1956 that scientists discovered the mutated gene that causes galactosemia. It is know that the mutated gene is found encoded on chromosome 9. In 1963, a major break- through was unearthed. Galactosemia was the second disorder found to be detectable through newborn screening. Finally, in 1970 galactosemia was acknowledged as a metabolic disease. Today scientists largely accept the notion that galactosemia is a rare metabolic disorder (disease).
This disorder comes in two different variations. Though there is more than one type, it is still rare, having only 1 in 100,000 births being affected by the disorder (Feinbloom). Classic Galactosemia is the first and more common form of the disorder. This is the form when the affected has a complete loss of the enzyme. Both parents must contribute a galactosemic gene for a child to receive the disorder. Since the accumulation of galactose behaves as a toxin in the body, serious complications such as an enlarged liver, kidney failure, cataracts, and brain damage may occur. Fortunately, the complications associated with classic galactosemia have not been associated with the variant of galactosemia, Duarte galactosemia. Duarte galactosemia is the most commonly know deviant to the classic form. The child with the Duarte variation inherits a gene for classic galactosemia from one parent and a Duarte variant gene from the other parent. The difference between the classic form and the variant is that the GALT in completely nonnative and the GALT in the Duarte I about 25-50% active("Duarte Galactosemia").
The diagnosis of Duarte galactosemia is usually made within the first two weeks of life by the same blood test used to detect the classic form. Symptoms typically start about the third day of life. The skin is jaundiced which doesn't go away with the usual procedures. Cataracts, enlarged liver, vomiting and failure to thrive (can lead to death) are probably the most common and apparent symptoms
At the end of 1998, cases of galactosemia were recorded in 24 different populations and ethnic groups in 15 countries worldwide. The mutations most frequently cited are Q188R, K285N, S135L, and N314D. Q188R is the most common mutation in European populations or in those predominantly of European descent. Generally, it accounts for 60-70% of mutant chromosomes, but there are significant differences in its relative frequency in individual populations. (Galactosemia)
A very strict diet is essential for galactosemics that suffer from the classic form. Once the disease is recognized, treatment consists of strictly avoiding all milk and milk-containing products. The infant can be fed with soy formula, meat-base formula, or other lactose-free formula. The condition is lifelong and requires abstinence from milk and milk products for life.
Parents need to take care and educate the child to avoid not only milk and milk products, but also those foods that contain dry milk products. For this reason, it is essential to read product labels and be an informed consumer. As for patients that suffer from Duarte Galactosemia, since the enzyme activity is between 25 and 50%, a strict diet is not needed, but a diet is recommended. Scientists have tried restricting lactose/galactose in the diet, and after a year, reintroducing them to test the person's response. This method of testing has been affective as to the ongoing research about both types of galactosemia and the limitations in both diets.