Galactosemia is a condition in which the body is unable to use (metabolize) the simple sugar galactose.

Galactosemia is an inherited disorder. This means it is passed down through families.

It occurs in approximately 1 out of every 60,000 births among Caucasians. The rate is different for other groups.

There are three forms of the disease:

• Galactose-1 phosphate uridyl transferase deficiency (classic galactosemia, the most common and most severe form)
• Deficiency of galactose kinase
• Deficiency of galactose-6-phosphate epimerase

People with galactosemia are unable to fully break down the simple sugar galactose. Galactose makes up half of lactose, the sugar found in milk. The other sugar is glucose.

If an infant with galactosemia is given milk, substances made from galactose build up in the infant's system. These substances damage the liver, brain, kidneys, and eyes.

Persons with galactosemia cannot tolerate any form of milk (human or animal). They must be careful about eating other foods containing galactose.