Conditions Classic Galactosemia

Classic galactosemia (GALT) is an inherited condition in which the body is unable to properly digest galactose, a sugar found in all foods that contain milk. If a child with GALT eats galactose, undigested sugars build up in the blood rather than being used for energy. If GALT is left untreated, it can cause seizures, serious blood infections, liver damage, or even death. However, when the condition is identified early in life and proper treatment is begun immediately, children with GALT often can lead healthy lives.

Galactosemia is a condition with multiple forms, each of which have different causes and outcomes. The type of galactosemia discussed on this page, classic galactosemia, is only one form of the condition. You can read about different types of the galactosemia on the pages for galactoepimerase deficiency and galactokinase deficiency.

Condition Type

Other Disorders


Classic galactosemia (GALT) occurs in 1 in every 30,000 to 60,000 newborns. GALT occurs in people of all ethnic groups, but it is most common in people of Irish descent.

Also known as

  • GALT
  • GALT Deficiency
  • Galactose-1-phosphate uridyltransferase deficiency
  • Galactosemia

Follow-Up Testing

Your baby’s doctor may ask you if your baby is showing any of the signs of GALT (see Early Signs below). If your baby has certain signs, your baby’s doctor may suggest starting immediate treatment.

If your baby’s newborn screening result for classic galactosemia (GALT) was out of the normal range, your baby’s doctor or the state screening program will contact you to arrange for your child to have additional testing. It is important to remember that an out-of-range screening result does not necessarily mean that your child has the condition. An out-of-range result may occur because the initial blood sample was too small or the test was performed too early. However, a few babies do have the condition so it is very important that you go to your follow-up appointment for a confirmatory test. Because the harmful effects of untreated GALT can occur within days after birth, follow-up testing must be completed as soon as possible to determine whether or not your baby has the condition.

Follow-up testing will involve a blood test and a urine test to measure the amount of certain substances present in your baby’s body. Undigested sugars build up in the body when a child has GALT, so measuring the amounts of these sugars and other substances can help doctors determine if your baby has a condition. Individuals with GALT have low levels of GALT enzyme and high amounts of undigested sugars in their body. Genetic testing for classic galactosemia may also be necessary to confirm the diagnosis.

About Classic Galactosemia

Early Signs

Signs of classic galactosemia (GALT) can appear within a few days after birth.

Early signs of GALT include:

  • Poor weight gain and growth (known as failure to thrive)
  • Poor feeding and sucking
  • Vomiting
  • Diarrhea
  • Sleeping longer or more often
  • Tiredness
  • Irritability
  • Low blood sugar (hypoglycemia)

Many of these signs may occur when your baby eats foods that their body cannot break down.

If your baby shows any of these signs, be sure to contact your baby’s doctor immediately.


Dietary Treatments

Your baby may need to avoid foods with lactose and galactose (sugars found in milk) to prevent the toxic build-up of undigested sugars in their blood. Many children with classic galactosemia (GALT) need to avoid all milk products.

Your baby’s doctor can recommend foods and formulas that do not contain lactose or galactose. This diet will likely need to continue through adulthood.

Certain medications, candies, fruits, and vegetables also contain galactose. Your baby may need to avoid these as well. A dietician or nutritionist can help you plan a healthy diet for your child.


Since many children must avoid milk-containing products, your baby may need to take calcium supplements. Your baby’s doctor may also prescribe Vitamin C and Vitamin K supplements.

Expected Outcomes

With early and careful treatment, your child will most likely have a healthy life. Starting treatment shortly after birth can help prevent developmental delays and intellectual disabilities. This is why newborn screening for classic galactosemia (GALT) is so important.

Some children with mild forms of GALT may not need any special treatment.

Even if a child avoids all foods that contain galactose, a small buildup of undigested sugars may still occur because the human body makes a small amount of this on its own. Some children with classic galactosemia who receive treatment early still show delays in learning, development, speech/language, and motor skills.

Without treatment, babies with GALT are at risk of developing vision trouble, liver trouble, low blood sugar (called hypoglycemia), blood infections, developmental delays, and intellectual disabilities. Babies who do not receive treatment can die within their first weeks or months of life.


When we eat food, enzymes help break it down. We need to break down the carbohydrates and sugars we eat so that they can be used for energy. Many foods, such as milk products and some fruits and vegetables, contain the sugar galactose. Galactose is broken down by several enzymes, including galactose-1-phosphate uridyl transferase (GALT enzyme).

If your baby has classic galactosemia (GALT), the GALT enzyme is either missing or not working correctly. When this enzyme does not work correctly, your baby’s body cannot break down galactose and undigested sugars build up in the blood. This build-up can damage important tissues and organs.

GALT is an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for GALT, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with GALT is rare, when both parents are carriers, they can have more than one child with the condition. Learn more about autosomal recessive inheritance.

Support for Classic Galactosemia

Support Services

Support groups can help connect families who have a child or other family member affected with classic galactosemia (GALT) with a supportive community of people who have experience and expertise in living with the condition. These organizations offer resources for families, affected individuals, health care providers, and advocates:

Accessing Care

Work with your baby’s doctor to determine the next steps for your baby’s care. Your baby’s physician may help you coordinate care with a doctor who specializes in metabolism, a dietician who can help plan your child’s specialized diet, or other medical resources in your community. Some children with classic galactosemia (GALT) have developmental delays. If you think that your baby is not meeting their developmental milestones, ask your baby’s doctor about the next steps in accessing a developmental evaluation and care.

Because GALT is a genetic condition, you may want to talk with a genetics specialist. A genetic counselor or geneticist can help you understand the causes of the condition, discuss genetic testing for GALT, and understand what this diagnosis means for other family members and future pregnancies. Speak with your baby’s doctor about getting a referral. The Clinic Services Search Engine offered by the American College of Medical Genetics and Genomics (ACMG) and the Find a Genetic Counselor tool on the National Society of Genetic Counselors (NSGC) website are two good places for you or your baby's health care provider to use to identify local specialists.

Families' Experiences

A mother tells the story of her daughter, Annabelles's galactosemia diagnosis through newborn screening. Read Annabelle's story here.

A second newborn heel prick confirmed Shyla's galactosemia diagnosis. Read Shyla's story here.

Galactosemia Midwest has gathered many stories about galactosemic kids. Read them here.

References & Sources

Visit GeneReviews for more information on classic galactosemia

Visit MedlinePlus Genetics for more condition information

Visit the Screening, Technology And Research in Genetics (STAR-G) Project for more information on GALT

Visit the National Newborn Screening and Global Resource Center (NNSGRC) for more condition information

ACT Sheets

Healthcare professionals can learn more about confirmatory testing by reading the American College of Medical Genetics and Genomics' Algorithm for Diagnosis and ACT Sheet, a guide for follow-up after newborn screening. You can visit this page of the ACMG website here.

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