What is Canavan disease?
– a rare inherited disorder that damages the ability of nerve cells (neurons) in the brain to send and receive messages
– affected infants appear normal for the first few months of life, but by age 3 to 5 months, problems with development become noticeable
– These infants usually do not develop motor skills such as turning over, controlling head movement, and sitting without support
– Other common features of this condition include weak muscle tone (hypotonia), an unusually large head size (macrocephaly)
– feeding and swallowing difficulties, seizures, and sleep disturbances may also develop.
Canavan’s disease has an autosomal recessive model of inheritance, which means that a child with the disease has inherited a copy of the mutated gene from each parent. Parents are carriers of the mutated gene, but generally do not show signs of disease.
Why Canavan's disease arises?
it is caused by mutations in the ASPA gene, which provides instructions for the production of an enzyme called aspartoacylase
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aspartoacylase normally cleaves a compound called N-acetyl-L-aspartic acid (NAA), which is predominantly found in neurons in the brain
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mutations in the ASPA gene reduce the function of aspartoacylase, which prevents normal degradation of NAA
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an excess of NAA in the brain is associated with symptoms of Canavan’s disease
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if NAA does not break down properly, the resulting chemical imbalance interferes with the formation of the myelin sheath during the development of the nervous system
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the accumulation of NAA also leads to the gradual destruction of existing myelin shells
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nerves without this protective cover fail, which disrupts normal brain development