What is galactosemia?

Galactosemia Chromosome Galactosemia is a rare disorder that affects the body's ability to break down a food sugar called galactose (found in milk and other dairy products).

The body breaks down lactose into galactose and glucose and uses these sugars for energy. Most people with galactosemia are missing an enzyme (called GALT) that helps further break down galactose. Defects in galactose metabolism cause toxic chemicals to build up in cells of the body.

How do people get galactosemia?

The most common form of the disorder, classic galactosemia, is passed down in an autosomal recessive pattern. To get the disorder, a child must inherit one defective copy of the gene from each parent. Inheriting one normal gene and one mutated gene makes a person a carrier. A carrier produces less of the GALT enzyme than normal, but is still able to break down galactose and avoid having symptoms of galactosemia. However, carriers can pass the mutated gene to their children.

What are the symptoms of galactosemia?

Defects in galactose metabolism can cause several severe symptoms, including kidney failure, an enlarged liver, cataracts (clouding of the eye lens), poor growth, and intellectual disability.

People can inherit a milder form of the disorder when a different gene, also involved in galactose metabolism, is mutated. These patients often suffer from cataracts, but not the other symptoms associated with classical galactosemia.

Autosomal Recessive

Galactosemia Pathway

How do doctors diagnose galactosemia?

In most states, babies are tested for galactosemia at birth. Using a tiny blood sample taken from the baby's heel, the test checks for low levels of the GALT enzyme. This allows for prompt treatment, which can substantially prevent the serious symptoms of this disorder.

For those families with a history of the disorder, a doctor can determine during a woman's pregnancy whether her baby has galactosemia (1) by taking a sample of fluid from around the fetus (amniocentesis), or (2) by taking a sample of fetal cells from the placenta (chorionic villus sampling or CVS).

How is galactosemia treated?

The only way to treat galactosemia is through dietary restrictions. People with the disorder must stay away from foods and drinks containing galactose, including milk, cheese, and legumes (dried beans).

Interesting facts about galactosemia

Galactosemia was first discovered in 1908 by the physician Von Ruess.

Classical galactosemia affects 1 in every 55,000 newborns.


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Genetic Science Learning Center (2014, June 22) Galactosemia. Learn.Genetics. Retrieved June 28, 2016, from
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