Classic galactosemia is an inherited disease. Due to a defective gene, there is a deficiency of the enzyme galactose-1-phosphate uridyltransferase. This enzyme is necessary for the conversion of galactose to glucose. Galactose is a simple sugar found in milk products. (The main sugar in milk is called lactose. It is made up of two simple sugars: galactose and glucose.) Glucose is the usable form of sugar in the human body.
Normally, the body converts galactose into glucose, which it then uses for energy. In galactosemia, galactose builds up in the blood. A buildup of galactose can cause severe damage to the liver, kidneys, central nervous system, and other body systems. If undetected, galactosemia is fatal.
A less severe form of this disease is Duarte galactosemia (also called galactokinase deficiency). This type may be managed with a few dietary restrictions. It does not carry the risk of neurologic or liver damage. However, the eye lens may be damaged, which can lead to cataracts.
This fact sheet describes classic galactosemia.
Galactosemia occurs when a child inherits a defective gene from each parent. Lacking a normal copy of this gene, the child cannot make one of the enzymes necessary to breakdown galactose.
A risk factor is something that increases your chance of getting a disease or condition. The primary risk factor for this condition is having parents who carry the gene for galactosemia.
An infant with classic galactosemia usually appears normal at birth. If galactosemia is not detected at birth with testing, symptoms usually occur within the first few days or weeks of life after the baby drinks breast milk or a lactose-containing formula.
Early symptoms may include:
- Jaundice (yellowing) of the skin and whites of the eyes
- Poor weight gain
- Feeding difficulties
If left untreated, later signs and symptoms may include:
- Opaque lenses of the eyes (cataracts)
- Enlarged liver
- Cirrhosis (scarring of the liver)
- Kidney problems
- Blood infections (septicemia)
- Swelling of the extremities or stomach
If diet restrictions are started immediately, it may be possible to prevent acute toxicity. However, long-term complications may still occur. These may include:
- Poor growth
- Learning disabilities
- Speech and language problems
- Fine and gross motor skill delays
- Ovarian failure (in girls)
Today, most US infants are screened for galactosemia at birth with a simple blood test. A small sample of blood is taken with a heel prick. It is also possible to diagnose galactosemia during pregnancy with an amniocentesis.
The diagnosis may also be suggested if a urine test shows the presence of galactose. The diagnosis can be confirmed with a blood test or with a biopsy of the liver or other tissues.
Galactosemia cannot be cured. But, you can take steps to prevent or minimize galactosemia symptoms and complications. The treatment is the strict avoidance of all sources of galactose. The most common source is lactose, which is the milk sugar that breaks down to galactose and glucose. To avoid all sources of galactose, closely monitor the following:
Diet–avoid all products that contain or produce galactose. This includes milk or milk by-products, such as:
- Lactose (milk sugar)
- Dry milk solids
This also includes some non-milk products, such as:
- Fermented soy products
- Organ meats
- Hydrolyzed protein
Lactose or galactose may be used as an additive in some food products. Therefore, always read food labels carefully in order to avoid these foods. Because galactose is so commonly found in foods, parents of a child who has galactosemia will nearly always require the services of a dietician skilled in advising about the management of this rare disorder.
Medications–check with your pharmacist to avoid medications that have fillers that contain galactose or lactose.
Supplements–avoid supplements unless prescribed by your doctor because fillers and inactive ingredients are not required to be listed in supplements. If you do take a supplement, check with your pharmacist to insure that there are no hidden sources of galactose in the product.
There is no known way to prevent galactosemia. If you have galactosemia or have a family history of the disorder, you can talk to a genetic counselor when deciding to have children.