Canavan Disease?
What is Canavan disease?
Canavan disease, one of the most common cerebral degenerative diseases of
infancy, is a gene-linked, neurological birth disorder in which the white matter of the brain degenerates into spongy tissue riddled with microscopic
fluid-filled spaces.
What causes Canavan disease?
Canavan disease is one of a group of genetic disorders
known as the leukodystrophies. These diseases cause imperfect growth or
development of the myelin sheath, the fatty covering that acts as an insulator
around nerve fibers in the
brain. Myelin, which lends its color to the "white matter" of the brain, is a
complex substance made up of at least ten different chemicals. Each of the
leukodystrophies affects one (and only one) of these substances. Canavan disease
is caused by mutations in the gene for an enzyme
called aspartoacylase.
What are the symptoms of Canavan disease?
Symptoms of Canavan disease, which appear in early
infancy and progress rapidly, may include:
- mental retardation,
- loss of previously acquired motor skills,
- feeding difficulties,
- abnormal muscle
tone (floppiness or
stiffness), and
- an abnormally large, poorly controlled head.
Paralysis,
blindness, or
hearing loss may also occur. Children are characteristically quiet
and apathetic. Although Canavan disease may occur in any ethnic group, it is
more frequent among Ashkenazi Jews from eastern Poland, Lithuania, and western
Russia, and among Saudi Arabians.
Canavan disease can be identified by a simple
prenatal blood test that screens for the missing enzyme or for mutations in the
gene that controls aspartoacylase. Both parents must be carriers of the
defective gene in order to have an affected child. When both parents are found
to carry the Canavan gene mutation, there is a
one in four (25%) chance with each pregnancy that the child will be affected with Canavan disease.
Next: Is there any treatment for Canavan disease? »
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