How can Canavan Disease be diagnosed?
There are many tests that may be performed to diagnose Canavan Disease. They include:
CT scan or MRI scan: To look for the degeneration of the white matter of the brain
Urine/blood/cerebrospinal fluid test: To look for increased N-acetyl-L-aspartate (NAA) in these fluids, suggesting a deficiency in the enzyme aspartoacylase (see genetic basis of disease, below)
Genetic testing for aspartoacylase gene mutations: Since the genetic basis of the disease is known to be a defect in the gene encoding aspartoacylase, the DNA of the child can be tested to look for mutations in this gene.
Can Canavan Disease be prenatally diagnosed?
Prenatal genetic diagnosis is possible by this method, and genetic counseling is recommended for prospective parents who have a family history of Canavan Disease. Parents can also be screened to see if they are carriers of the disease.
What are the symptoms of Canavan Disease?
Below is a list of the clinical terms of some of the symptoms and pathologies of Canavan Disease, along with definitions of each term as necessary. Please keep in mind that severity and symptoms will vary, and so all children will not have all symptoms.
Hypotonia: Decreased muscle tone (in Canavan disease, this particularly occurs inthe neck)
Hyperextension of the legs: legs are kept abnormally straight
Flexion of the arms: arm muscles tend to be flexed
Megalocephaly: enlarged head (also called macrocephaly)
Reflux with vomiting
Failure to thrive
Seizures: The brain controls how the body moves by sending electrical signals. Seizures (also called convulsions) occur when the normal signals from the brain are changed. Severity of a seizure can vary dramatically. Some people may only shake slightly and do not lose consciousness. Other people may become unconscious and have violent shaking of the entire body.
Severe mental retardation
What is the prognosis of Canavan Disease?
Canavan Disease is progressive, and death will usually occur within the first two decades of life.
How is Canavan Disease treated?
Treatment is to ameliorate the symptoms of the disease. There is no cure for Canavan Disease.
What is the Genetic Basis of Canavan Disease?
Canavan Disease is inherited in an autosomally recessive fashion. It is caused by a deficiency in the gene encoding a protein called aspartoacylase. Aspartoacylase in needed to break down N-acetyl-L-aspartate (NAA), a molecule that is thought to be involved in the removal of water from certain types of brain cells, as well as in the formation of myelin lipids. If the NAA is not broken down (as in Canavan disease), the excess levels of NAA lead to an increase in osmotic pressure in certain types of brain cells and causes demyelination..
Canavan Disease can be found in people of all ethnicities. However, it has especially high prevalence among Ashkenazi Jewish people; the frequency of carriers is thought to be approximately 1 in every 40 within this population.
Other Clinical Names for Canavan Disease
Although Canavan Disease is the most common term used to describe this leukodystrophy, you may encounter other names for it. Other clinical names of Canavan Disease include:
- Aspartoacylase Deficiency
- Spongy Degeneration of the Brain
- van Bogaert-Bertrand Spongy Degeneration of the Brain