Galactosemia

Definition

Galactosemia is a condition in which the body is unable to use (metabolize) the simple sugar galactose.

Alternative Names

Galactose-1-phosphate uridyl transferase deficiency; Galactokinase deficiency; Galactose-6-phosphate epimerase deficiency

Causes, incidence, and risk factors

Galactosemia is an inherited disorder. This means it is passed down through families.

It occurs in approximately 1 out of every 60,000 births among Caucasians. The rate is different for other groups.

There are three forms of the disease:

• Galactose-1 phosphate uridyl transferase deficiency (classic galactosemia, the most common and most severe form)
• Deficiency of galactose kinase
• Deficiency of galactose-6-phosphate epimerase

People with galactosemia are unable to fully break down the simple sugar galactose. Galactose makes up half of lactose, the sugar found in milk. The other sugar is glucose.

If an infant with galactosemia is given milk, substances made from galactose build up in the infant's system. These substances damage the liver, brain, kidneys, and eyes.

Persons with galactosemia cannot tolerate any form of milk (human or animal). They must be careful about eating other foods containing galactose.

Symptoms

Infants with galactosemia can develop symptoms in the first few days of life if they eat formula or breast milk that contains lactose. The symptoms may be due to a serious blood infection with the bacteria E. coli.

• Convulsions
• Irritability
• Lethargy
• Poor feeding (baby refuses to eat formula containing milk)
• Poor weight gain
• Yellow skin and whites of the eyes (jaundice)
• Vomiting

Signs and tests

Signs include:

• Amino acids in the urine and/or blood plasma (aminoaciduria)
• Enlarged liver (hepatomegaly)
• Fluid in the abdomen (ascites)
• Low blood sugar (hypoglycemia)

Newborn screening in many states will test for this condition.

Tests include:

• Blood culture for bacteria infection (E. coli sepsis)
• Enzyme activity in the red blood cells
• Ketones in the urine
• Prenatal diagnosis by directly measuring the enzyme galactose-1-phosphate uridyl transferase
• "Reducing substances" in the infant's urine, and normal or low blood sugar while the infant is being fed breast milk or a formula containing lactose

Treatment

People with this condition must avoid all milk, milk-containing products (including dry milk), and other foods that contain galactose for life. It is essential to read product labels and be an informed consumer.

Infants can be fed with:

• Soy formula
• Meat-based formula or Nutramigen (a protein hydrolysate formula)
• Another lactose-free formula

Calcium supplements are recommended.

Support Groups

Parents of Galactosemic Children, Inc.

www.galactosemia.org

Expectations (prognosis)

People who get an early diagnosis and strictly avoid milk products can live a relatively normal life. However, mild intellectual impairment may develop, even in people who avoid galactose.

Complications

• Cataracts
• Cirrhosis of the liver
• Death (if there is galactose in the diet)
• Delayed speech development
• Irregular menstrual periods, reduced function of ovaries leading to ovarian failure
• Mental retardation
• Severe infection with bacteria (E. coli sepsis)
• Tremors and uncontrollable motor functions

Calling your health care provider

Call your health care provider if:

• Your infant has a combination of galactosemia symptoms
• You have a family history of galactosemia and are considering having children

Prevention

It is helpful to know your family history. If you have a family history of galactosemia and want to have children, genetic counseling will help you make decisions about pregnancy and prenatal testing. Once the diagnosis of galactosemia is made, genetic counseling is recommended for other members of the family.

Many states screen all newborns for galactosemia. If parents learn that the test indicates possible galactosemia, they should promptly stop giving their infant milk products and ask their health care provider about having a blood test done for galactosemia.

visHeader

References

Berry GT, Segal S, Gitzelmann R. Disorders of Galactose Metabolism. In: Fernandes J, Saudubray JM, van den Berghe G, Walter JH, eds. Inborn Metabolic Diseases: Diagnosis and Treatment. 4th ed. New York, NY: Springer;2006:chap 7.