What Is Galactosemia?

Medically Reviewed by Renee A. Alli, MD on September 04, 2023
4 min read

Breast milk is full of good things that babies need -- key nutrients, hormones, and antibodies that protect them from disease and keep them healthy.

But some babies are born with galactosemia. It’s a rare metabolic condition that prevents them from processing galactose (one of the sugars in breast milk and formula) and turning it into energy. The disorder can cause many problems for newborns and can be life-threatening if left untreated.

It’s easy to test for galactosemia. It’s also simple to treat once it’s diagnosed. And children who have it can live normal lives.

Galactosemia is hereditary. Both parents must pass it down for their child to get it.

If your baby has this condition, it means the genes that produce the enzymes to break down galactose into glucose (a sugar) are missing key parts. Without these parts, the genes can’t tell the enzymes to do their job. This causes galactose to build up in the blood, creating problems, especially for newborns.

There are three main types of galactosemia:

  • Classic (type I)
  • Galactokinase deficiency (type II)
  • Galactose epimerase deficiency (type III)

Type I occurs in about 1 in every 30,000 to 60,000 people. Type II and type III are less common.

As a parent or potential parent, you and your partner can be genetically screened for galactosemia. If you’re a carrier, it doesn’t mean you have to avoid galactose. But it means you can pass galactosemia along to your children if your partner is also a carrier.

If your newborn has classic galactosemia, they’ll appear normal at birth. Symptoms start to show up within a few days after they begin to drink breast milk or formula with lactose -- the milk sugar that contains galactose.

Your baby first loses their appetite and starts vomiting. Then they get jaundice, a yellowing of the skin and the whites of their eyes. Diarrhea is common, too. The disease leads to severe weight loss and your baby struggles to grow and thrive.

Without treatment, over time your child may develop cataracts and can be susceptible to infections. They may have liver damage and kidney problems. Their brain may not mature well. That can cause developmental disabilities. Some children have issues with their motor skills and muscles. For girls, it can cause their ovaries to stop working. Most with this condition can’t have children.

Every baby born at a U.S. hospital is given what’s called a newborn screening. A blood sample is taken from a heel stick (a tiny cut in the baby’s foot) and it is tested for several conditions. Galactosemia is one of them.

If your baby shows signs of the illness, your doctor will suggest a follow-up test to confirm. This test will include both a blood and urine sample.

If your child has galactosemia, your doctor will work with you to plan a diet. Lactose and galactose are taken out of their diet. Instead, they’re given soy-based formula and must avoid milk or milk byproducts. Your doctor will likely refer your child to a specialist.

Though a person with galactosemia will never be able to process this type of sugar, they can live normal lives if the disease is caught early enough.

Along with eliminating dairy, your doctor may recommend cutting out some fruits, vegetables, and candies that contain galactose. In addition, your child may need to take vitamin and mineral supplements such as calcium, vitamin C, vitamin D, and vitamin K.

Some babies have a form of the condition called Duarte galactosemia (DG), which is milder than the classic form (type I). Babies with DG may have some issues processing galactose but a recent showed that changing the diet change may not be necessary and most babies do fine continuing breastfeeding or continuing formula with galactose.. 

Babies with type II or type III also will have fewer issues than babies with classic galactosemia. However, they still can develop cataracts, kidney and liver issues, and have delayed growth. Girls with galactosemia may require hormone treatment when they reach puberty.

It’s important that parents of a child with galactosemia work with a health care team to find ways to help them live with the condition and its effects on their daily life.