Galactosemia Health Article

Definition

Galactosemia is an inherited disease in which the body is unable to metabolize the simple sugar galactose, which is found primarily in dairy products but is also produced by the body. If left unaddressed, galactose can increase to toxic levels in the body and may lead to damage of the liver, central nervous system, and various other body systems.

Description

Galactosemia is a rare but potentially life-threatening disease resulting from the body's inability to metabolize galactose. Galactose makes up half of lactose, the sugar that is found in milk. Persons with galactosemia either have very low levels of or are entirely lack the enzyme that assists the body in breaking down galactose. This enzyme is called galactose-1-phosphate uridyl transferase (GALT). The GALT enzyme enables the body to break down galactose into glucose for energy. The severity of the disease may vary from person to person, because some individuals with galactosemia have higher levels of this enzyme than do others.

The two main types of galactosemia are called classic and Duarte variant. Individuals with the classic type of galactosemia lack the enzyme activity necessary to metabolize galactose. Individuals with the Duarte variant have approximately 5–20 percent of the enzyme activity necessary to metabolize this sugar and often do not have signs or symptoms of galactosemia.

Transmission

Galactosemia is an hereditary disease. In order to understand this disorder, it is necessary to have a very basic knowledge of genetics. Genes, the basic components of hereditary material, contain the "blueprint" that directs the development and functioning of every cell and tissue in the human body. Genes are situated on larger structures called chromosomes that contain several thousand genes each. Genes and chromosomes exist in pairs. Every cell in the body has 23 pairs of chromosomes containing two copies of every gene. Human beings receive one copy of every gene from their mother, and another copy from their father. Most of the time, genes function normally. However, in some cases, a change or mutation in a gene can cause it to not function. These mutations can cause inherited or genetic disorders.

In galactosemia, the gene mutation which occurs is inherited in what is known as an autosomal recessive pattern. This means that a non-working copy of the gene must be inherited from both parents for a child to be affected with the disease. The parents of children are called "carriers" of the disorder, because though they themselves do not have galactosemia, they may have children who do.

Unfortunately, as of 2004, parents had no way of knowing if they carry the mutated gene that causes galactosemia until they have a child diagnosed with the disease. The chance that two parents each of whom has the defective gene will produce a child with a recessive disorder is one in four or 25 percent with each pregnancy. The chances that their child will be a carrier, like themselves, is one in two, or 50 percent, with each pregnancy.