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Canavan´s disease

Canavan’s disease was named after Myrtelle Canavan who first described this disease in 1931. Since this time the genetic and biochemical background of this disease has been studied and researched. New developments through genetic testing allow for a definite diagnosis of Canavan. It is also possible to identify a potential carrier of this genetic disease. Canavan is found especially in the ethnic group of the Ashkenazi Jews. Statistics show that every 57 th person in this particular group is a carrier and can pass on Canavan’s. This disease occurs randomly in other population groups as well especially people of Eastern European descent.

What causes Canavan’s disease

Every person has two sets of chromosomes. One set is passed on by the mother, the other by the father. This means that nearly every gene exists twice. For some hereditary diseases only one compromised gene will already cause the disease to break out (dominant gene).

Canavan is passed on through a recessive gene. That means that both parents need to pass on their defective gene to then create this disease in their child. Unfortunately one can be a carrier without showing any signs of the disease at all. Carriers have one defective and one healthy gene and therefore appear to be healthy. 2% of all men and women who are Ashkenzi Jews carry a defective gene. If these women and men have children with each other the chance of having a child that will be a carrier as well is 50%. There is a 25% chance that these children will become ill of Canavan’s disease.

The gene that causes this disease has been identified as part of the 17 th chromosome. Because of a defect there is not enough of an enzyme called Aspartocyclase. This enzyme is responsible for breaking down an acid (NAA). As NAA accumulates, it then interferes with the production of Myelin. Myelin isolates the nerve endings in the brain. This progressive disease creates spongy tissues in the brain – the brain degenerates.

Symptons of Canavan’s disease

Clinical symptoms are typically present during early childhood. Some of the early symptoms can include an increase in head size ( Macrencephaly) and abnormal muscle tone. While these are typical effects they are not always present. As the disease progresses blindness, paralysis and seizures may also occur. Babys show difficulties nursing and swallowing. Final stages of the disease create complete paralysis. The patient can not communicate in any form and finally dies of apnea - paralysis of the lungs. Currently there is no known cure for Canavan’s disease.