Definition

Classic galactosemia type I is a metabolic disorder. It causes a low level or lack of an enzyme called galactose-1-phosphate uridyltransferase. This enzyme changes galactose to glucose. Galactose is a simple sugar found in milk products. Glucose is the usable form of sugar in the human body.

Since there is not enough of the enzyme, galactose builds up in the blood. This build up can cause severe damage to the liver, kidneys, central nervous system, and other body systems. If undetected, galactosemia is fatal.

Type II is a less severe form of this disease due to low levels of galactose kinase. This type may be managed with a few dietary restrictions. It does not carry the risk of neurologic or liver damage.

Type III is a form with variable severity due to low levels of galactose epimerase. This type can cause cataracts, delayed growth and development, intellectual disability, liver disease, and kidney problems.

This sheet will focus on classic galactosemia.

Causes

Galactosemia is a genetic condition. It is caused by faulty genes that are inherited from both parents. At least one normal copy of these genes is needed to make the enzyme correctly.

Risk Factors

The primary risk factor is having parents who carry the gene for galactosemia.

Symptoms

An infant with classic galactosemia usually appears normal at birth. Symptoms usually occur within the first few days or weeks of life after the baby drinks breastmilk or a lactose-containing formula.

Early symptoms may include:

• Yellowing of the skin and whites of the eyes
• Vomiting
• Poor weight gain
• Feeding difficulties
• Irritability
• Convulsions

If left untreated, later symptoms and complications may include:

• Opaque lenses of the eyes known as cataracts
• Enlarged liver
• Enlarged spleen
• Intellectual disability
• Sepsis caused by a specific bacteria
• Scarring of the liver— cirrhosis
• Liver failure
• Kidney problems
• Swelling of the extremities or abdomen

If dietary restrictions are started right away, it may be possible to prevent acute toxicity. However, long-term complications may still occur. These may include:

• Poor growth
• Learning disabilities
• Speech and language problems
• Fine and gross motor skill delays
• Ovarian failure
• Cataracts—usually regress with dietary treatment, leaving no remaining visual impairment
• Decreased bone mineral density—usually from lack of dairy products

Diagnosis

Most infants in the US are screened for galactosemia at birth. A small sample of blood is taken with a heel prick. If this screen is positive further testing will be done to confirm the diagnosis. This may include genetic testing.

It is also possible to diagnose galactosemia during pregnancy with an amniocentesis. This test is only done if the baby is at high risk for an illness or condition.

Amniocentesis Copyright © Nucleus Medical Media, Inc.

Your doctor may also suspect galactosemia after a urine test. The diagnosis can be confirmed with a blood test, including enzyme levels, or with a biopsy of the liver or other tissues.

Treatment

Galactosemia cannot be cured. Steps can be taken to prevent or minimize symptoms and complications.

Prevention

There is no known way to prevent galactosemia. You may consider genetic counseling if you have galactosemia or have a family history of the disorder. The counselor can help you determine the risk of passing the condition to your children.