Gene : GALT

What is Galactosemia?

Galactosemia is an inherited disorder caused by the body's inability to break down galactose, a simple sugar found in milk, breast milk and other foods. Classic galactosemia, the most common and severe form of this disorder, is caused by deficiency of the galactose-1-phosphate uridyltranferase (GALT) enzyme. Persons with this disorder have too much galactose in the blood, which causes life-threatening complications including brain damage, liver enlargement, kidney failure, and cataracts. Treatment for galactosemia is best begun within the first days of life. If infants with classic galactosemia are treated promptly with a low-galactose diet, most of the complications can be prevented. Patients with galactosemia have a normal lifespan with proper treatment and diet restriction, although they are still at risk for cataracts, developmental delay, speech problems and premature ovarian insufficiency in women. Classic galactosemia is caused by pathogenic variants in the GALT gene.

How is Galactosemia inherited?

Galactosemia is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for galactosemia. However, the risk to have a child affected with galactosemia is increased. Testing of reproductive partners is recommended for carriers of galactosemia.

How common is Galactosemia?

Classic galactosemia is estimated to affect about 1 in 30,000 newborns.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
  • Copy number analysis: exons 5 & 10
Affected Systems






Carrier Rates
Detection Rate
Carrier Frequency
African American > 95% 1 in 78
Ashkenazi Jewish > 95% 1 in 172
East Asian > 95% 1 in 500
General Population > 95% 1 in 110
Northern European Caucasian > 95% 1 in 108

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