May also be called: Galactose-1-Phosphate Uridyltransferase Deficiency; Galactokinase Deficiency; Galactose-6-Phosphatase Emirase Deficiency; GALT Deficiency; Galactose Epimerase Deficiency; Classic Galactosemia; Galactosemia Type II; Galactosemia Type III Galactosemia (guh-lak-tuh-SEE-mee-uh) is an inherited disorder in which the body can't break down a type of sugar called galactose. More to Know Galactose is one of the two sugars found in lactose, or milk sugar. It's also in some fruits and vegetables. Galactosemia is caused by mutations (changes) in genes that help make enzymes the body needs to change galactose into glucose. The parents of a child with galactosemia are carriers of the mutation. This means they have the gene in their bodies and can pass it on, but won't show any signs of the condition themselves. Babies with galactosemia don't have the enzyme that changes galactose into glucose, a sugar the body uses. If babies drink milk or other products with lactose or galactose, galactose can build up in the body and damage cells and organs. This can lead to blindness, impaired mental development, growth problems, and in some cases even death. Galactosemia usually appears within the first few days or weeks after a baby's birth. Newborns with galactosemia often have symptoms like vomiting, poor feeding, loss of appetite, yellowed skin and whites of the eyes (jaundice), and failure to thrive (they don't grow and gain weight properly). They also may have enlarged livers (hepatomegaly). To treat galactosemia, milk (including breast milk), other dairy products, and other sources of lactose and galactose must be removed from the baby's diet. This may help control symptoms. Even with the proper dietary changes, though, galactosemia often causes serious long-term problems. Keep in Mind If not treated, galactosemia quickly can become life-threatening. Fortunately, newborns can be screened for the condition. Treatment usually starts before a child becomes seriously ill and has permanent organ damage. Children who are diagnosed early and eat a lactose-free and galactose-free diet usually reach adulthood. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles Prenatal Genetic Counseling Genetic counselors work with people who are either planning to have a baby or are pregnant to determine whether they carry the genes for certain inherited disorders. Find out more. Read More Genetic Testing Advances in genetic testing help doctors diagnose and treat certain illnesses. The type of test done depends on which condition a doctor checks for. Read More When Your Baby Has a Birth Defect If your child has a birth defect, you don't have to go it alone - many people and resources are available to help you. Read More Newborn Screening Tests Newborn screening tests look for health conditions that aren't apparent at birth. Find out which tests are done. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.