Classic galactosemia type I is a metabolic disorder. It causes a low level or lack of an enzyme called galactose-1-phosphate uridyltransferase. This enzyme changes galactose to glucose. Galactose is a simple sugar found in milk products. Glucose is the usable form of sugar in the human body.

Since there is not enough of the enzyme, galactose builds up in the blood. This build up can cause severe damage to the liver, kidneys, central nervous system, and other body systems. If undetected, galactosemia is fatal.

Type II is a less severe form of this disease due to low levels of galactose kinase. This type may be managed with a few dietary restrictions. It does not carry the risk of neurologic or liver damage.

Type III is a form with variable severity due to low levels of galactose epimerase. This type can cause cataracts, delayed growth and development, intellectual disability, liver disease, and kidney problems.

This sheet will focus on classic galactosemia.

Galactosemia is a genetic condition. It is caused by faulty genes that are inherited from both parents. A normal copy of these genes is needed to make the enzyme correctly.