Canavan disease

Alternative names 
Spongy degeneration of the brain; Aspartoacylase deficiency

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

Causes, incidence, and risk factors

Canavan disease is inherited as an autosomal recessive trait. It is more common among Ashkenazi Jews than in the general population.

A deficient enzyme, aspartoacylase, results in the accumulation of N-acetylaspartic acid in the brain. This causes a degeneration of the white matter.

Typically, symptoms begin in the first year of life. Parents tend to notice when a child is not reaching particular developmental milestones, including poor muscle tone and lack of head control. Eventually, the child can develop feeding problems, seizures, and loss of vision.

Although death often occurs before 18 months of age, some live until they are teenagers or, rarely, young adults.

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

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

Additional information and resources are available from:

Canavan Foundation
http://www.canavanfoundation.org
877-4-CANAVAN

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 and should be considered if both parents are of Ashkenazi Jewish descent. For this latter group, DNA testing can almost always tell if one or both parents is a carrier.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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