Canavan disease

Definition:

Canavan disease is an inherited disorder of aspartic acid metabolism that is characterized by degeneration of the white matter of the brain.

Alternative Names:

Spongy degeneration of the brain; Aspartoacylase deficiency

Causes, incidence, and risk factors:

Canavan disease is inherited as an autosomal recessive trait and has a higher incidence among Ashkenazi Jews than the general population. A deficient enzyme, aspartoacylase, results in the accumulation of N-acetylaspartic acid in the brain and subsequent degeneration of the white matter. Typical cases have onset of symptoms in the first year of life with loss of developmental milestones and death before 18 months of age.

Symptoms:

A family history of Canavan disease
Decreased muscle tone (hypotonia), especially of the neck muscles
Abnormal posture with flexed arms and straight legs
Feeding difficulties
Nasal regurgitation
Swallowing difficulties
Reflux with vomiting
Increasing head size (macrocephaly)
Head lag
Failure to meet milestones
Seizures
Severe mental retardation
Blindness
Death often by 18 months

Signs and tests:

Hyperreflexive
Joint stiffness
Optic atrophy

Tests:

Head CT showing degeneration of white matter (leukodystrophy)
Head MRI scan showing degeneration of white matter (leukodystrophy)
Urine chemistry, increased N-acetylaspartic acid (increased secretion)
CSF chemistry, increased N-acetylaspartic acid (increased levels)
Blood chemistry, increased N-acetylaspartic acid (increased levels)
Genetic testing for aspartoacylase gene mutations

Treatment:

Treatment aims to ease the symptoms of the disease. There is no specific treatment.

Support Groups:

Canavan Foundation, Inc. 877-4-CANAVAN; http://www.canavanfoundation.orgwww.canavanfoundation.org

Expectations (prognosis):

With Canavan disease, the central nervous system degenerates, and progressive disability is likely. Death usually occurs in the first 1 to 2 decades of life.

Complications:

This is often a fatal disorder and includes severe disabilities such as mental retardation, blindness, and inability to walk.

Calling your health care provider:

Call your health care provider if your child has any symptoms of Canavan disease.

Prevention:

Genetic counseling is recommended for prospective parents with a family history of Canavan disease. The carrier state for Canavan disease can be diagnosed by enzyme analysis of skin fibroblasts. Prenatal diagnosis is possible.

Review Date: 10/26/2001
Reviewed By: David G. Brooks, M.D., Ph.D., Division of Medical Genetics, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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