Galactosemia

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at January 2, 2017
StartDiseasesGalactosemia

Galactosemia is a rare hereditary metabolic disorder. Children born with this disorder lack, or produce too little, of the liver enzyme, GALT, which is needed to process the simple sugar galactose. Galactose is found in many foods including breast milk and dairy foods. Small amounts of this simple sugar are also produced by the human body.

Contents

Definition & Facts

Galactosemia is rare. At present an estimated 1 in 30,000 to 60,000 infants born in the United States are affected. This disorder was first described by Friedrich Goppert in the early 1900’s. By the 1950’s, Herman Kalckar and his team had identified the cause and testing began in parts of the United States. In America, newborn screening for galactosemia has been a routine part of infant care for over a decade.

There are several variations of this condition including classic galactosemia, galactokinase deficiency, and epimerase deficiency. Symptoms range from mild to severe and appear within the first days of life. Without treatment, the condition can be fatal. A carefully monitored diet can alleviate many of the symptoms and promote normal growth and development.

Type I - or classic galactosemia - is the most severe. Symptom onset occurs quickly and up to 75% of untreated cases are fatal. Type II – also known as galactokinase deficiency – is less severe and generally results in milder symptoms. Most commonly, infants with Type II galactosemia will develop cataracts. Type III, or galactose epimerase deficiency, is an underproduction of the enzyme. Symptoms can vary from mild to severe. Early dietary changes can reduce risks of side effects and long-term developmental issues in all forms of this condition. 

Symptoms & Complaints

Symptoms of galactosemia are a result of the build-up of galactose in the body. These symptoms appear within days of birth. The most common symptoms include:

If left untreated - or if treatment is delayed - the effects of galactosemia become more severe and long lasting. Common complications of galactosemia include cataracts, low blood sugar or hypoglycemia, low or impaired immunity, sepsis - or shock - from infection, liver damage, and abnormal bleeding. In addition, developmental delays such as mental retardation, speech disabilities, difficulty walking, or loss of balance are possible. Finally, untreated galactosemia can result in convulsions and death in up to 75% of untreated cases. 

Causes

The cause of galactosemia is a genetic disorder known as GALT gene deficiency. GALT is a liver enzyme that enables the body to break down galactose. When GALT is not present or too little is produced by the body, the result is a toxic buildup of galactose in the blood that leads to the complications and symptoms associated with galactosemia. GALT gene deficiency is caused by a pair of recessive genes, so for a child to be born with galactosemia, both parents must be carriers of the gene mutation. Though galactosemia is found in all populations, those with Irish ancestry are more likely to be carriers.

Diagnosis & Tests

Galactosemia can be diagnosed during pregnancy. In the United States, however, screening for galactosemia is most commonly done in the hospital at the time of birth. When the baby is born, a doctor will collect a drop of blood with a needle prick to the child’s foot. In this test, doctors look for the presence of GALT in the blood. Galactosemia can also be diagnosed through clinical urine tests and symptom observation. It should be noted that symptoms can be deadly within days and early detection is thus important.

Treatment & Therapy

Early diagnosis and treatment is essential in cases of galactosemia. There is no cure, so treatment for galactosemia is focused on management of the condition. Those with the condition undergo regular blood tests and urine tests to ensure that galactose is not building up in the body at toxic levels.

Adherence to a strict diet is a must. This diet includes the avoidance of any dairy or milk containing products. In some cases, soy is also avoided. Babies cannot be breast-fed because breast milk also contains galactose. They may be given a soy or hypoallergenic formula instead. This is a lifelong condition, so dietary supplements such as calcium and vitamin D may also be required to maintain overall health. A nutritionist can help patients with galactosemia create and manage a healthy diet.

It is also advisable that young children wear a medical alert bracelet to notify caregivers of the condition. This helps avoid accidental exposure. With early detection and treatment patients with galactosemia can avoid many of the health risks and go on to live normal, healthy lives.

Prevention & Prophylaxis

Prevention of galactosemia is focused on risk-management because there is no way to prevent parents from passing on the recessive gene to offspring. To manage the risk, however, couples may choose to undergo genetic testing and genetic counseling prior to pregnancy to determine the risks of offspring being born with the condition. If both parents are carriers of the recessive gene, there is a 1:4 chance that the child will be born with galactosemia.

There are several options available for parents who are carriers of the gene. Parents may choose to become pregnant and have the fetus genetically tested. At this point, parents have the option of continuing or terminating the pregnancy. Parents may also choose to undergo in vitro fertilization (IVF) to manage the risks of having a child born with the condition. A genetic counselor can advise prospective parents on all the options available.