Galactosemia

What happens in galactosemia

Lactose, the main sugar in milk, is split in the gut into glucose and galactose. Galactose is then converted into glucose by a chain of three enzymes. In classic galactosemia, the second enzyme, GALT, is missing or nearly inactive.

Without GALT, galactose and its byproducts, especially galactose-1-phosphate and galactitol, build up. They damage the liver, kidneys, brain and the lens of the eye, and weaken the newborn's defenses against bacteria.

It is an autosomal recessive condition: a child must inherit a non-working copy of the GALT gene from each parent. When both parents are carriers, each pregnancy has a 1 in 4 chance of an affected child.

Types of galactosemia

Symptoms in babies

In classic galactosemia, symptoms start within the first few days of milk feeding:

• Poor feeding and vomiting
• Lethargy and floppiness
• Jaundice (yellow skin and eyes) that is worse or longer-lasting than usual newborn jaundice
• An enlarged liver and swollen belly
• Easy bleeding or bruising from liver damage
• Poor weight gain
• Cataracts (clouding of the lens; see congenital cataracts), sometimes visible within weeks

A serious danger is E. coli sepsis (neonatal sepsis), a bloodstream infection that babies with galactosemia are especially prone to. It can appear before the screening result is back. Untreated, classic galactosemia can lead to liver failure, brain swelling and death.

Diagnosis

• Newborn screening: a heel-prick blood test in the first days of life measures GALT enzyme activity and, in some programs, galactose levels. All US states screen for it.
• Confirmation: measuring GALT activity in red blood cells, galactose-1-phosphate levels, and genetic testing of the GALT gene.
• Important caveat: a blood transfusion can cause a false-normal screening result, so testing may be repeated later.

Because babies can become ill before results arrive, doctors stop milk feeds immediately in any sick newborn in whom galactosemia is suspected.

Treatment

Immediate

• Stop breast milk and all cow's milk formula right away.
• Start a soy-based infant formula or another galactose-free specialist formula.
• Treat complications: antibiotics for sepsis, vitamin K and plasma for bleeding, fluids and liver support.

Most acute symptoms, including jaundice, liver swelling and early cataracts, improve within days to weeks.

Lifelong diet

• Avoid all dairy products and foods with milk, lactose, whey, casein, milk solids or butter.
• Read labels carefully: lactose is used in many processed foods and some medicines.
• Current international guidelines allow galactose from non-dairy sources, such as fruit, vegetables, legumes and mature cheeses with negligible lactose (such as some aged hard cheeses). Older advice to avoid these is no longer recommended, because the body makes more galactose itself than these foods supply.
• Calcium and vitamin D supplements are usually needed to protect bones.

"Lactose-free" milk is not safe, because the lactose has been split into glucose and galactose, and the galactose remains.

Ongoing monitoring

A metabolic specialist and dietitian follow children regularly. Monitoring includes galactose-1-phosphate levels, development, speech, eyes, bone health and, in girls, puberty.

Long-term complications

Even with a strict diet from early infancy, many people with classic galactosemia develop problems, probably because the body makes some galactose on its own:

• Speech problems, especially childhood apraxia of speech
• Learning difficulties and lower IQ in some, though many attend mainstream school
• Tremor and movement problems
• Primary ovarian insufficiency in most girls and women, causing delayed puberty or early menopause and reduced fertility. Hormone therapy is often needed.
• Low bone density
• Anxiety and depression

Frequently asked questions

What foods should be avoided with galactosemia?

All milk and dairy products, including breast milk, cow's and goat's milk, yogurt, ice cream, butter and most cheeses, plus foods listing milk, lactose, whey, casein or milk solids. Lactose-free milk is not safe. Fruits, vegetables and legumes are generally allowed under current guidelines.

Is galactosemia the same as lactose intolerance?

No. Lactose intolerance is a common, harmless shortage of the gut enzyme lactase that causes bloating and diarrhea. Galactosemia is a rare inherited metabolic disorder in which galactose cannot be processed by the body, causing toxic buildup that damages organs.

Can a baby with galactosemia be breastfed?

No, not with classic galactosemia. Breast milk contains lactose, which releases galactose. Babies need a galactose-free formula, usually soy-based. Babies with the Duarte variant can often be breastfed, depending on the metabolic team's advice.

What is Duarte galactosemia?

Duarte galactosemia is a milder variant in which the GALT enzyme works at reduced but significant levels. Most children have no symptoms. Many specialist centers now recommend no dietary restriction, though practice varies, so families should follow their metabolic clinic's advice.

What is the life expectancy with galactosemia?

With early diagnosis and diet, most people with classic galactosemia live into adulthood with a near-normal life expectancy. The main challenges are long-term developmental, speech and ovarian problems rather than shortened life.