This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Galactosemia, which means “galactose in the blood,” refers to a group of inherited disorders that impair the body’s ability to process and produce energy from a sugar called galactose. When people with galactosemia injest foods or liquids containing galactose, undigested sugars build up in the blood. Galactose is present in many foods, including all dairy products (milk and anything made from milk), many baby formulas, and some fruits and vegetables. The impaired ability to process galactose can be due to the deficiency of any of 3 enzymes, caused by mutations in different genes. There are 3 main types of galactosemia which are distinguished based on their genetic causes, signs and symptoms, and severity:
There is also a “variant” of classic galactosemia called Duarte variant galactosemia, in which a person has mutations in the GALT gene but has only partial deficiency of the enzyme. Infants with this form may have jaundice, which resolves when switched to a low-galactose formula. Some studies have found that people with this form are at increased risk for mild neurodevelopmental problems, but other studies have found there is no increased risk. The risk may depend on the extent of the deficiency.
Inheritance of all types of galactosemia is autosomal recessive. The diagnosis may be suspected based on symptoms or results of newborn screening tests, and can be confirmed by measuring enzyme activity and genetic testing. Depending on the type of galactosemia, treatment may involve removing galactose from the diet (as soon as the disorder is suspected), calcium supplementation, and individualized care for any additional symptoms. The long-term outlook for people with galactosemia varies depending on the type, symptoms present, and commitment to the diet.
For more information, visit GARD.