Galactosemia

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Overview, Causes, & Risk Factors

Galactosemia is an inherited disorder (transmitted as an autosomal recessive trait). It occurs at a rate of approximately 1 out of 60,000 births. There are 3 forms of the disease -- galactose-1 phosphate uridyl transferase deficiency (classic galactosemia) and deficiency of galactose kinase or galactose-6-phosphate epimerase. Of these, the galactose-1-phosphate transferase deficiency is the most severe (and more common).

People with galactosemia are unable to fully metabolize the simple sugar galactose. Galactose makes up half of the sugar, called lactose, that is found in milk. Lactose is called a disaccharide (di meaning 2 and saccharide meaning sugar) since lactose is made up of two sugars, galactose and glucose, bound together.

If an infant with galactosemia is given milk, derivatives of galactose builds up in the infants system causing damage to the liver, brain, kidneys, and eyes. Individuals with galactosemia cannot tolerate any form of milk (human or animal), or must carefully watch intake of other galactose-containing foods. Exposure to milk products may result in liver damage, mental retardation, cataract formation, and kidney failure.

After drinking milk for a few days, a newborn infant with galactosemia, will develop intolerance of feeding, jaundice, vomiting, lethargy, irritability, and convulsions. The liver is enlarged and the blood sugar may be low. Continued feeding of milk products to the infant leads to cirrhosis of the liver, cataract formation in the eye (which may result in partial blindness), and mental retardation.