Galactosemia is a rare genetic metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly. Lactose in food (such as dairy products) is broken down by the enzyme lactase into glucose and galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose are severely diminished or missing entirely, leading to toxic levels of galactose 1-phosphate in various tissues as in the case of classic galactosemia, resulting in an enlarged liver, cirrhosis, renal failure, cataracts, brain damage, and ovarian failure. Without treatment, mortality in infants with galactosemia is about 75%.
Infants are routinely screened for galactosemia in the United States, and the diagnosis is made while the person is still an infant. Infants affected by galactosemia typically present with symptoms of lethargy, vomiting, diarrhea, failure to thrive, and jaundice. None of these symptoms are specific to galactosemia, often leading to diagnostic delays.
The incidence of galactosemia is about 1 per 60,000 births for Caucasians. In other populations the incidence rate differs. Galactosemia is also very common within the Irish Traveller population. This disorder is inherited in an autosomal recessive manner, meaning a child must inherit one defective gene from each parent to show the disease.
Galactose is converted into glucose by the action of three enzymes. If a deficiency occurs in any of these enzymes the conversion process does not function properly. We offer testing for the GALT gene which provides instructions for making the enzyme galactose-1-phosphate uridyl transferase. This enzyme is part of the galactose conversion process.
Methodology: Sequencing entire coding region which includes 5kb deletion and 8 common mutations
Purpose:Confirmation of Clinical Diagnosis
ICD-10 Code E74.21
Test Requisition: Sequencing Requisition
CPT Code: 81406 Cost: $535.00
Turn-around-time: 14 days
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2. Miriam Murphy, Brian McHugh, Orna Tighe, Philip Mayne, Charles O'Neill, Eileen Naughten and David T Croke. Genetic basis of transferase-deficient galactosaemia in Ireland and the population history of the Irish Travellers. European journal of Human Genetics. July 1999, Volume 7, Number 5, Pages 549-554.
3. Galactosemia The University of Utah, Genetics Science Learning Center. 2008
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