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Genetic and Rare Diseases Information Center (GARD)

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Other Names for this Disease
  • Galactose-1-phosphate uridyltransferase deficiency
  • Galactosemia, classic
  • GALT deficiency
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Galactosemia, which means “galactose in the blood”, is a rare inherited condition. People with galactosemia have problems digesting a type of sugar called galactose from the food they eat. Because they cannot break galactose down properly, it builds up in their blood. Galactose is found in milk and all foods that contain milk. Galactosemia occurs when an enzyme, called ‘galactose-1-phosphate uridyl transferase’ (GALT), is either missing or not working properly. Without enough GALT enzyme activity, galactose cannot be changed to glucose so it builds up in the blood in large amounts.[1]

There are different types of galactosemia: classic galactosemia (also known as type I and is the most common and most severe form of the condition), galactosemia type II (also called galactokinase deficiency), and type III (also called galactose epimerase deficiency). The different types of galactosemia is caused by mutations in the GALT, GALE, and GALK1 genes and is inherited in an autosomal recessive fashion.[1][2]
Last updated: 6/9/2011


  1. Genetic Fact Sheets for Parents: Galactosemia. STAR-G. Accessed 5/27/2011.
  2. Galactosemia. Genetics Home Reference. January 2008; Accessed 6/9/2011.
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Basic Information

  • Genetics Home Reference (GHR) contains information on Galactosemia. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The National Organization for Rare Disorders (NORD) is a federation of more than 130 nonprofit voluntary health organizations serving people with rare disorders. Click on the link to view information on this topic.
  • The Screening, Technology And Research in Genetics (STAR-G) Project has a fact sheet on this condition, which was written specifically for families that have received a diagnosis as a result of newborn screening. This fact sheet provides general information about the condition and answers questions that are of particular concern to parents.

In Depth Information

  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Galactosemia. Click on the link to view a sample search on this topic.