What is Galactosemia?

Classic galactosemia is the most common and most serious form of the condition. It happens when the body doesn’t make enough of an enzyme called GALT, which is needed to break down galactose.

This condition is inherited, which means both parents must carry the gene for a child to be affected. If both parents are carriers, there’s a 1 in 4 chance their child will have classic galactosemia.

The Duarte variant is a milder type of galactosemia. It also involves a change in the GALT gene, but the enzyme still works a little—about 25% as well as it should.

Most people with the Duarte variant don’t have serious symptoms. Some may need to limit galactose in their diet for a while, especially as babies, but many do not need long-term treatment.

This type of galactosemia happens when the body doesn’t make enough of an enzyme called galactokinase. Without it, the body can’t fully break down galactose.

Not all newborn screening tests check for this form of the condition. That means a baby could have a normal screening result but still have galactokinase deficiency.

Epimerase deficiency is a rare form of galactosemia caused by changes in the GALE gene. This affects how well the body can process galactose.

There are three types of this deficiency—generalized, intermediate, and peripheral. The generalized type is the most serious and is similar to classic galactosemia.

Like some other types, this one is often not picked up by standard newborn screening tests.

A baby with galactosemia may start showing symptoms just a few days after drinking breast milk or formula that contains lactose.

Early signs include tiredness, vomiting, diarrhea, irritability, and not wanting to eat. The baby may lose weight or show signs of dehydration. Jaundice (yellowing of the skin or eyes), swelling in the belly, and liver problems can also happen.

If not treated, the condition can lead to serious problems like seizures, muscle weakness, cataracts, and liver damage.

Even with early treatment, children with galactosemia may face long-term challenges. Common issues include delays in learning to talk, trouble with reading or math, and problems with movement or coordination.

Some people also develop nervous system problems, like shaky hands, poor balance, or muscle stiffness.

Most girls and women with classic galactosemia have trouble with their ovaries. This often leads to early menopause and infertility later in life.

In the U.S., many states test newborns for galactosemia shortly after birth. These tests use a small blood sample to check for signs of the condition.

Doctors may also run other tests, such as checking the baby’s urine or looking at how well certain enzymes are working. In some cases, they may test for infections caused by bacteria like E. coli, which can appear in babies with galactosemia.

People with galactosemia need to avoid all foods and drinks that contain lactose or galactose. Babies should not have breast milk or regular formula—they can use special formulas like soy or lactose-free options instead.

As they grow, children and adults must read food labels carefully and avoid dairy and other products with galactose. Doctors may also suggest calcium supplements to support bone health.

Some children may need speech therapy or other support as they get older.

Galactosemia is rare. It affects about 1 in 16,000 to 1 in 48,000 newborns worldwide, depending on how it’s diagnosed.

It can occur in people of any background, but it’s more common in people with Irish ancestry. The Duarte variant is most often seen in African-Americans and people in South Africa.

With early diagnosis and a strict diet, many people with galactosemia can live healthy lives.

Still, even with treatment, some children may have learning delays, speech problems, or trouble with movement. Most women with classic galactosemia are unable to have children due to early ovarian failure.