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Classic galactosemia

(Classic • guh-LAK-toh-SEE-mee-uh)

General Condition Information

Other Names

  • Classical galactosemia
  • Galactosemia
  • Galactosemia (Classical)
  • Transferase deficient galactosemia (classical)

Condition Type

Birth Prevalence

  • It is estimated that less than 90 babies are born with this condition each year in the United States. 
  • Visit GeneReviews to learn more about how often this condition occurs.

Screening Finding

Absent or low galactose-1-phosphate uridylyltransferase (GALT) enzyme activity with or without high total galactose

What is Classic galactosemia

Classic galactosemia is an inherited (genetic) condition that prevents the body from breaking down a sugar called galactose. 

Your body gets energy from breaking down galactose in milk and other foods. Several enzymes break down galactose into other substances that your body can use or remove.

There are different types of galactosemia: 

The type your baby has depends on which enzyme is not working properly to break down galactose. 

Classic galactosemia is the most common type of galactosemia and results when an enzyme called GALT, which processes galactose, does not work correctly. 

Milder forms of classic galactosemia include: 

  • Clinical variant galactosemia: People with this form have a small amount of working GALT enzyme, and can process some galactose, but not enough to avoid symptoms.
  • Duarte galactosemia: People with this form have enough working GALT enzyme to experience either mild symptoms or no symptoms at all.

When you cannot break down galactose, undigested sugars build up in the body and can cause damage. If untreated, this damage can cause the signs and symptoms of the condition.

Newborn Screening and Follow-Up

Condition Details

Treatment and Management

It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.

Treatments may include the following:

  • Avoidance of foods that contain galactose and lactose
  • Avoidance of all dairy products
  • Special foods and formulas
  • Vitamin supplements (calcium, vitamin K, vitamin D)

Children who receive early and ongoing treatment for classic galactosemia can have healthy growth and development. Some children with classic galactosemia who receive treatment early still show delays in learning, development, speech/language, and motor skills.

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