Krabbe disease

Definition

Krabbe disease is a rare genetic disorder of the nervous system. It is a type of leukodystrophy.

Alternative Names

Globoid cell leukodystrophy; Galactosylcerebrosidase deficiency; Galactosylceramidase deficiency

Causes

A defect in the GALC gene causes Krabbe disease. Persons with this gene defect do not make enough of a substance called galactocerebroside beta-galactosidase (galactosylceramidase).

The body needs this substance to make myelin, the material that surrounds and protects nerve fibers. Without it, myelin breaks down, brain cells die, and nerves in the brain and other body areas do not work properly.

There are two forms of Krabbe disease.

• Early-onset Krabbe disease appears in the first months of life. Most children with this form of the disease die before they reach age 2.
• Late-onset Krabbe disease begins in late childhood or early adolescence.

Krabbe disease is inherited, which means that it runs in families. To get this disease, each of your parents must pass you a copy of the faulty GALC gene. (See: Autosomal recessive pattern)

This condition is very rare. It is most common among people of Scandinavian descent.

Symptoms

Early-onset Krabbe disease:

• Changing muscle tone from floppy to rigid (decerebrate posturing)
• Hearing loss that leads to deafness
• Failure to thrive
• Feeding difficulties
• Irritability and sensitivity to loud sounds
• Severe seizures (may begin at a very early age)
• Unexplained fevers
• Vision loss that leads to blindness
• Vomiting

Late-onset Krabbe disease:

Vision problems may appear first, followed by walking difficulties and rigid muscles. Symptoms vary from person to person. Other symptoms may occur.

Exams and Tests

An exam of the retina in the eye may show damage to the optic nerve. There may be signs or deafness and abnormal posturing in the late stages of the disorder.

Tests that may be done include:

• Blood test to look for galactosylceramidase levels in white blood cells
• CSF total protein
• MRI of the head
• Nerve conduction velocity
• Testing for the GALC gene defect

Treatment

There is no specific treatment for Krabbe disease.

Some people have had a bone marrow transplant in the early stages of the disease, but this treatment has risks.

Support Groups

United Leukodystrophy Foundation -- www.ulf.org

Outlook (Prognosis)

The outcome is likely to be poor. On average, infants with early-onset cases die before age 2. People who develop the disease at a later age have survived into adulthood with nervous system disease.

Possible Complications

This disease damages the central nervous system. It can cause:

• Blindness
• Deafness
• Severe problems with muscle tone

The disease is usually life threatening.

When to Contact a Medical Professional

Call your health care provider if your child develops symptoms of this disorder. Seizures, loss of consciousness, or abnormal posturing may be emergency symptoms.

Prevention

Genetic counseling is recommended for persons with a family history of Krabbe disease who are considering having children.

A blood test can be done to see if you carry the gene for Krabbe disease.

Prenatal tests (amniocentesis or chorionic villus sampling) can be done to screen a developing baby for this condition.

References

Vanier M. Disorders of sphingolipid metabolism. In: Fernandes J, Saudubray J-m, van den Berghe G, Walter JH, eds. Metabolic Diseases: Diagnosis and Treatment. 4th ed. New York, NY:Springer; 2006:chap 38.

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