Krabbe disease (KRAH-buh disease) is an inherited, often fatal disorder affecting the central nervous system. Krabbe disease affects about 1 in every 100,000 people in the United States.
The disease affects muscle tone and movement, and may cause vision and hearing loss, among other devastating effects. In most cases, Krabbe disease develops in babies before 6 months of age, although it can occur in older children and in adults.
There's no cure for Krabbe disease and treatment mainly involves approaches designed to ease symptoms. However, early studies using stem cell transplants to treat Krabbe disease before symptoms begin have had some success.
Early-onset Krabbe disease
Late-onset Krabbe disease
As a general rule, the younger the age that Krabbe disease occurs, the faster it progresses. Some people diagnosed during adolescence or adulthood may have less-severe symptoms, with muscle weakness as a primary symptom. They may have no impairment of their cognitive abilities.
When to see a doctor
Krabbe disease is caused by a genetic defect that results in a deficiency in an enzyme called galactocerebrosidase (GALC). This enzyme is essential for the maintenance of myelin — a fatty substance that insulates your nerve fibers.
Doctors sometimes refer to Krabbe disease as globoid cell leukodystrophy. Globoid cells store molecules called galactolipids. Without GALC, galactolipids accumulate in the brain. Psychosine is a type of galactolipid, and it's the one suspected of causing the most damage in Krabbe disease. The damage occurs because when psychosine levels are high, the cells that produce myelin begin to self-destruct.
A child needs to inherit an abnormal gene from each parent to trigger the disorder. This inheritance pattern is called autosomal recessive. The gene for Krabbe disease is located on chromosome 14.
Autosomal recessive inheritance pattern
To have an autosomal recessive disorder, you inherit two mutated genes, one from each parent. These disorders are usually passed on by two carriers. Their health is rarely affected, but they have one ...
Krabbe disease is caused by a defective gene that must be inherited from both parents. But even if both parents have the defective gene, a child may not develop Krabbe disease.
If both parents are carriers of the defective gene for Krabbe disease, their offspring have a 25 percent risk of developing the disorder. If a child inherits the gene from only one parent, he or she will be a carrier but will never develop symptoms.
Krabbe disease occurs more often in people from Israel than in the population at large.
A number of complications — including infections and respiratory difficulties — can develop in children whose Krabbe disease has progressed. In the later stages of the disease, children become incapacitated, confined to their beds, and eventually lapse into a vegetative mental state.
Most children who develop Krabbe disease in infancy die before the age of 2 years old, most often from respiratory failure or complications of immobility and markedly decreased muscle tone. Children in whom the disease develops later in childhood may have a somewhat longer life expectancy, usually between two and seven years after diagnosis.
Preparing for your appointment
Depending on the initial signs and symptoms your infant or child exhibits, you may first be seen in an emergency room, or by your family doctor or pediatrician. However, ongoing care for Krabbe disease is usually provided by a doctor who specializes in disorders of the nervous system (neurologist).
Here's some information to help you get ready for your child's appointment, and what you can expect from your child's doctor.
What you can do
Preparing a list of questions ahead of time can help you make sure you cover the points that are most important to you. For Krabbe disease, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
Tests and diagnosis
Your child's doctor will conduct a physical exam, evaluating signs and symptoms that may indicate Krabbe disease, and then conduct a number of diagnostic tests.
Your child's doctor will take a blood sample and obtain a skin sample (biopsy), and send both to a laboratory for analysis. There, a lab technician will measure the activity of the GALC enzyme. If GALC activity level is low, your child may have Krabbe disease.
Although the results of these tests can help the doctor make a diagnosis, they don't provide evidence of how quickly the disease may progress. For example, a very low GALC activity finding doesn't always mean that the condition will advance rapidly.
To confirm the diagnosis, your child's doctor will recommend one or more of the following tests:
Before birth, a fetus can be screened for Krabbe disease. To do this, your doctor withdraws amniotic fluid surrounding the fetus using a needle. The cells in the amniotic fluid are examined in the lab. A prenatal diagnosis of Krabbe disease can be made by evaluating the activity of GALC enzymes found in these cells or by genetic mutation analysis.
Prenatal diagnosis is not for everyone. When a family has had a previously affected child, then looking for an enzyme deficiency or mutations may be feasible, but this is not recommended when there isn't a family history.
Treatments and drugs
There's no specific, proven treatment for Krabbe disease, nor is there a cure. Krabbe disease treatment is designed primarily to ease symptoms and may include:
Treating symptoms in some older children with less-severe forms of the disease may include:
Bone marrow transplantation
For other children — particularly infants who have already developed symptoms — this treatment hasn't been successful. It doesn't appear to halt or slow progression of the disease in babies, nor has it been effective in treating fetuses diagnosed with the disease before birth.
More research — including longer follow-up with more subjects — is needed to better assess the possible benefits of this treatment.
Cord blood transfusion
In small studies, doctors have transfused healthy donor cells with normal enzyme (GALC) activity into babies with Krabbe disease who have not yet developed symptoms. This treatment has stimulated normal development of myelin in these babies. Babies treated before symptoms appeared seemed to maintain normal hearing and vision; however, there was subsequent deterioration in language expression and in motor skills, such as walking or picking up objects.
In the future, gene therapy could play a role in the treatment of Krabbe disease, by delivering a functional gene via a virus to the cells or tissue, replacing the abnormal gene that is responsible for the disorder.
Coping and support
Having a child with Krabbe disease may be one of the most difficult things you'll ever have to cope with, and some people find it easier if they don't do it alone. The United Leukodystrophy Foundation offers online support and connections to other families dealing with Krabbe disease. The organization's number is 800-728-5483 or you can visit the website at www.ulf.org.
Last Updated: 2011-06-11
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