Galactosemia means “galactose in the blood”. This inherited disorder prevents your body from breaking down the sugar galactose, causing it to build up to toxic levels in your blood. People with galactosemia have to avoid dairy products, breast milk and most baby formulas. Galactosemia can be life-threatening to infants if they aren't diagnosed quickly.


What is galactosemia?

Galactosemia is an inherited metabolic disorder that makes your body unable to process a sugar called galactose. Galactosemia can be a problem for newborns because galactose is present in both breast milk and most baby formulas. It’s important to catch it early to avoid the complications of the disease, which can be serious and even life-threatening. U.S. hospitals screen for the condition at birth. With early diagnosis and a lactose-restricted diet, people with galactosemia can go on to lead relatively normal lives.


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How does this condition affect my child’s body?

When your child is unable to break down the galactose in their food, it begins to build up in their blood. (Galactosemia literally means “galactose in the blood.”) As it builds up, it overflows into places it shouldn’t go. An enzyme that is not supposed to be involved with galactose converts it to galactitol, an alcohol derivative that is toxic to the body. As toxic galactitol accumulates in your child’s organs and tissues, it can cause serious damage. If left untreated, galactosemia leads to a cascade of side effects, including:

Children who receive an early diagnosis and treatment usually grow and develop adequately. Some may not seem any different from other children, but others may still have some difficulties. That’s because even on a galactose-free diet, it’s impossible to eliminate all galactose from the body. Your body naturally produces a certain amount (endogenous galactose,) which can continue to cause problems. Children receiving treatment for galactosemia may continue to have:

  • Speech delays.
  • Learning disabilities.
  • Behavioral problems.
  • Balance and coordination problems (ataxia).
  • Tremors.
  • Hormone deficiencies, leading to delayed puberty in people assigned female at birth.

How does galactosemia affect adults?

Adults with galactosemia can live relatively normal lives, but those who experienced symptoms as children may continue to experience lifelong symptoms. Some symptoms may come and go depending on how well adults maintain their restricted diet. Others, such as hormone deficiencies, are common despite treatment.

Most women and people assigned female at birth who have galactosemia will have primary ovarian insufficiency, even with early diagnosis and treatment. They may have difficulties getting pregnant and carrying a baby to term. Many require hormone replacement therapy in order to have their period. Hormone replacement can also help with fertility issues.


Who does galactosemia affect?

Galactosemia is a genetic disorder. It can affect anyone who inherits the mutated genes (one from each parent). If both of your parents are carriers of the mutated gene, you have a 25% chance of inheriting galactosemia. This condition happens around the world, in all ethnic groups.

How common is this condition?

Classic galactosemia is rare. It occurs in approximately 1 in 45,000 people.

A milder variant known as Duarte galactosemia is more common. Duarte galactosemia is more of a sensitivity to galactose than a real intolerance. It affects about 1 in 4,000 people.


Symptoms and Causes

What are the signs and symptoms of galactosemia?

In newborns, signs of classic galactosemia begin to appear after a few days of feeding. Symptoms can be mild or severe and may include:

These symptoms require immediate medical attention. After a healthcare provider diagnoses galactosemia and you remove galactose from your baby’s diet, these symptoms should improve.

What causes galactosemia?

Galactosemia happens because of a gene mutation. You have to inherit it from both parents to get it. Each parent provides one copy of the mutated gene. But unless both copies of their galactosemia genes are mutated, the parents typically won’t have symptoms of the condition themselves, so symptoms in their baby can come as a surprise.

The mutated gene fails to produce the enzymes necessary to break down galactose for energy. This causes chemical products of galactose to accumulate in your body. There are three different genes involved that may be mutated. Each corresponds to a different type of galactosemia.

What are the different types of galactosemia?

Type I (Classic)

The classic version of galactosemia, which is also called type I, is the most common and also the most severe. Type I is caused by a mutation in the GALT gene. This gene is responsible for making the enzymes that break down galactose into glucose and other molecules that your body can use for energy. The type I gene mutation essentially eliminates this enzyme activity, leaving your body unable to process galactose at all. This causes galactose to accumulate quickly in your body.

Type II (Galactokinase deficiency)

A mutation of the GALK1 gene causes the type II variant. This gene makes enzymes that play a supportive role in galactose metabolism. Type II causes fewer medical problems than the classic type. The primary risk from type II is that you may develop cataracts.

Type III (Galactose epimerase deficiency)

The GALE gene, which produces enzymes that also play a supportive role in galactose metabolism, causes type III galactosemia. Any shortage of these important enzymes will eventually lead to accumulation of galactose in your body. Type III can manifest with mild or severe symptoms. The more severe version can lead to many of the more serious complications of classic galactosemia, including cataracts, developmental delays, intellectual disabilities, liver disease and kidney problems.

Duarte galactosemia

Duarte galactosemia happens due to mutations in the GALT gene, the same gene that causes classic galactosemia. It’s simply a less severe mutation. It reduces but doesn’t eliminate the essential enzyme function responsible for metabolizing galactose. People with Duarte galactosemia may have some digestive difficulties from foods containing galactose, but they don’t have the same medical complications. They don’t necessarily have to avoid galactose in their diet.

Diagnosis and Tests

How is galactosemia diagnosed?

In the U.S. it is standard procedure to screen newborn babies for a list of disorders — including classic galactosemia — that can cause significant damage before symptoms appear. (This is sometimes called the PKU test, which refers to phenylketonuria, another condition this test can detect.) The screening is done by pricking your baby’s heel and drawing a little blood, usually about 24 hours after they are born. If your child has galactosemia, the blood test will show reduced GALT enzyme activity in their blood. Your healthcare team will follow up these results with genetic testing to identify the type of galactosemia your child has.

Management and Treatment

How do you treat galactosemia?

The only known way to treat galactosemia is to eliminate galactose from your diet. Galactose is a component of lactose, so this usually means avoiding dairy products. Newborns can receive a soy-based or elemental formula. Children and adults may need to supplement their calcium and vitamin D intake to make up for the lack of dairy products in their diet. Supplementing with calcium and vitamin D helps to maintain bone density.

What treatment will my child require for long-term side effects of galactosemia?

Some children may require extra support with learning and development as they grow up. This might include:

  • Speech therapy.
  • Occupational therapy.
  • Behavioral therapy.
  • Targeted learning plans.

Teenagers may require hormone therapy in order to induce puberty and menstruation.


Can galactosemia be prevented?

You can’t control whether you or your child inherits the condition. But you and your partner can undergo genetic testing for the gene variant before having biological children. You can be a carrier without having galactosemia yourself. If you know in advance that you’re a carrier of the gene, you can plan for the likelihood that you will pass it on to your children. Genetic counseling can help you understand what this might mean for your genetic family. Early detection is the best way to minimize complications from the condition.

Outlook / Prognosis

What is the life expectancy of someone with galactosemia?

With early diagnosis and a galactose-free diet, life expectancy is normal. However, if permanent organ damage occurred during the newborn period, this will affect your long-term health outlook.

Living With

How do adults living with galactosemia take care of themselves?

The key to health for anyone living with galactosemia is maintaining a galactose-free diet. This takes discipline, and many adults benefit from joining communities where they can discuss and share recipes. Many also appreciate the social support, especially if they continue to experience long-term symptoms.

Adults with galactosemia may see their regular healthcare provider more often and take periodic assessments to check for signs and symptoms of the disease. These may include:

Regular testing enables adults to catch deficiencies earlier and treat them before they progress.

A note from Cleveland Clinic

Galactosemia is rare, but it is predictable with genetic screening. If you are pregnant or planning to conceive, prenatal testing can tell you if you or your partner carry the genes involved in galactosemia. The chance of passing it on to your child is 25% if both of you have the gene. Knowledge is power and can help you plan accordingly to prevent the most severe complications of the disease.

If your newborn recently received this diagnosis, you may be processing many emotions, including shock and overwhelm. Galactosemia is often a surprise, especially when you have no known family history of the disease. Knowledge of the condition is relatively low even among healthcare providers, in part because it is so rare. But with early diagnosis, the worst effects of galactosemia have already been averted.

With appropriate diet, your child is likely to have a relatively normal life. Some developmental hurdles may occur, requiring extra therapy. These are the kinds of unpredictable challenges that parents can face for many different reasons on the journey of parenthood. With a known condition, you have the benefit of anticipating these challenges, allowing you to recognize them and intervene earlier for better outcomes.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 08/25/2022.

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