AtoZ Diseases

What is this condition?

Galactosemia is the name for any disorder that interferes with the body’s ability to metabolize galactose, the sugar found in milk. This disorder produces symptoms ranging from cataracts and liver damage to mental retardation. It occurs in two forms: classic galactosemia and galactokinase-deficiency galactosemia.

Although a galactose-free diet relieves most symptoms, galactosemia-induced mental impairment is irreversible, and the person may have some vision loss. Caught early, the condition can be stopped by changing from milk-based to meat- or soy-based formulas.

What causes Galactosemia?

Both forms of galactosemia are inherited as recessive traits and occur in about 1 in 60,000 births in North America. However, up to 1.25% of the population has the gene that may lead to classic galactosemia. The second form, galactokinase-denciency galactosemia, is rarer. In both forms, inability to normally metabolize the sugar causes galactose accumulation and damage. The mechanism of this defect is still unknown.

What are its symptoms?

Children who inherit the classic galactosemia gene show symptoms at birth or a few days after they start nursing. The symptoms are a failure to thrive, vomiting, and diarrhea. Other effects include yellow skin and eyes, protein in the urine, and cataracts.

If the child continues to drink milk or eat galactose-containing foods, he or she may develop mental retardation, malnourishment, and progressive liver failure and may eventually die. Although treatment may prevent mental impairment, the condition can produce a short attention span, cataracts, difficulty with spatial and mathematical relationships, and apathetic, withdrawn behavior.

How is it diagnosed?

The doctor will order blood tests and urine tests to check for evidence of both types of galactosemia, but the measurements must be precise. Some infants who consume large amounts of milk have elevated blood galactose levels but don’t have the condition. Also, new­borns excrete galactose in their urine for about a week after birth; premature infants, even longer. Other tests include biopsy of liver tissue samples and enzyme tests. Amniocentesis, the sampling of the amniotic fluid that’s done before the infant is born, is recommended when parents are known to have the gene.

How is it treated?

If galactose and lactose are eliminated from the infant’s diet, most of the symptoms disappear. The infant gains weight and the cataracts shrink. If a child has the disorder, the doctor will advise replacing cow’s milk formula or breast milk with a meat-based or soy-based formula. As the child grows, a balanced, galactose-free diet must be maintained.

A pregnant woman who carries the gene should also follow a galactose-restricted diet. Such a diet supports normal growth and development and may delay symptoms in the infant. If the parents of a child with galactosemia want to have another child, the doctor will recommend genetic counseling. In some states, screening of all new­borns for galactosemia is required by law.

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