Krabbe Disease is a leukodystrophy, a group of more than 15 rare genetic disorders that cause progressive degeneration of the white matter of the brain due to imperfect growth or destruction of the myelin sheath, the fatty covering that insulates nerve fibers in the brain and spinal cord and promotes rapid transmission of nerve impulses. Without myelin, nerve cells cease to function and eventually die. As myelin deteriorates in leukodystrophies such as Krabbe disease, nervous system function is impaired. The leukodystrophies are often referred to as “demyelinating” diseases.
Krabbe disease (also called globoid cell leukodystrophy) is a degenerative disorder caused by the shortage (deficiency) of an enzyme called galactosylceramidase. This enzyme deficiency impairs the growth and maintenance of myelin and is also characterized by the abnormal presence of globoid cells, which are globe-shaped cells that usually have more than one nucleus.
The symptoms of Krabbe disease usually begin before the age of 1 year (the infantile form). Initial signs and symptoms typically include irritability, muscle weakness, feeding difficulties, episodes of fever without any sign of infection, stiff posture, and slowed mental and physical development. As the disease progresses, muscles continue to weaken, affecting the infant’s ability to move, chew, swallow, and breathe. Affected infants also experience vision loss and seizures.
Less commonly, onset of Krabbe disease can occur in childhood, adolescence, or adulthood (late-onset forms). Visual problems and walking difficulties are the most common initial symptoms in this form of the disorder, however, signs and symptoms vary considerably among affected individuals.
In the United States, Krabbe disease affects about 1 in 100,000 individuals. A higher incidence (6 cases per 1,000 people) has been reported in a few isolated communities in Israel.
The most common leukodystrophies include Canavan disease, Krabbe disease, metachromatic Leukodystrophy (MLD), Childhood Ataxia with Central Nervous System Hypomyelination (CACH), Alexander disease and Refsum disease.