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Canavan disease

Canavan's disease (CD) is a progressive hereditary metabolic disease that begins in childhood. In this disease, the insulation layer around the offshoots (myelin / white matter) of nerve fibers in the brain gradually becomes damaged (leukodystrophy). An essential enzyme (aspartoacylase enzyme) is missing, which disrupts the proper transmission of nerve signals.

As a result, a child becomes increasingly ill and can even die.

It is caused by changes in the DNA: in the ASPA gene (17p13.3), which encodes the aspartoacylase enzyme.

Mild forms of Canavan's disease are usually composite heterozygotes with one mild and one severe mutation. When one says heterozygous, it means that there are two different packets of information on one gene. The gene pair then consists of two dissimilar genes.

 

Autosomaal recessive inheritance

The disease inherits autosomal recessive. The healthy gene predominates. Only when a child inherits an incorrect gene from both parents does it get the disease. The chance of a sick child is 25%. The chance of a healthy child is also 25%. The chance of becoming a carrier of the disease is 50%.

 

There are two forms and they differ in severity:

  • Neonatal / infantile form
    • Shortened life expectancy
    • This form is most common
    • Noticeable in the first months after birth
    • Delay in development
    • (often) a large head and the head circumference increases
    • Lack of control over the muscles of the head
    • Decreased visual response speed
    • Muscle weakness (hypotonia)
    • Later stiffer muscles (hypertonia spasticity)
    • Difficulty crawling, sitting, walking
    • Trouble swallowing and eating
    • Trouble seeing
    • Sometimes blindness
    • Sometimes deafness
    • Trouble sleeping
    • Sometimes seizures
    • Sometimes paralysis

 

  • Mild / juvenile form
    • Normal life expectancy
    • Some trouble talking
    • Some difficulty moving

Research

Based on the characteristics and suspicion of Canavan's disease, the doctor can request scans of the brain: CT scan or an MRI.
Canavan's disease can also often be diagnosed with blood and urine tests or a biopsy. After that, genetic testing can often confirm the diagnosis.

Common in people of Ashkenazi Jewish descent

Canavan's disease was most common in persons of Ashkenazi (German and Eastern European) Jewish descent. It is estimated that 1 in 40 Ashkenazi Jews is a carrier of the Canavan gene. It also occurs in other ethnic groups. There is now a very good screening program among people of Ashkenazi descent.

 

Prevalence of the disease

About 1 in 100,000 children have Canavan's disease. In children of Ashkenazi Jewish origin, that number is 1 in 6,400 to 1 in 13,500 children.

Other names

Canavan-Van Bogaert-Bertrand disease
Aspartoacylase deficiency
ASPA deficiency
N-Acetylaspartate aciduria
Aspartoacylase deficiency
ASPA deficiency
ASP deficiency
Aminoacylase 2 deficiency
ACY2 deficiency
Spongy degeneration of the brain
Spongy degeneration of central nervous system