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| Canavan Disease |
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What is Canavan disease ? Canavan disease (CD) is an inherited (genetic) disease. It occurs due to a deficiency of the enzyme called Aspartoacylase, since the gene which usually tells the body to produce this enzyme is faulty. Babies are born apparently unaffected. At 2 to 4 months of age, he/she develops poor head control and seizures. Other symptoms are observed before the age of 6 months such as loss of grasping reflex, smiling and increased head circumference. Death usually occurs before 36 months. Who gets Canavan disease ? Genetic diseases are often more common in specific community groups. CD is most common amongst descendants of Central and Eastern European (Ashkenazi) Jews. What causes Canavan disease ? Canavan disease is a disease caused by inheriting a 'double-dose' of a faulty in a gene (called ASPA) which codes for Aspartoacylase. Every person has two copies of this gene in each cell of their body. A person will only be affected by CD if s/he has a mutation in both copies of the ASPA gene. This can only happen if one faulty copy is inherited from each parent. One in every 40 Ashkenazi Jews carries one copy of the faulty gene and one regular copy of the gene. In the general population, however, only about one in 300 people carry a faulty copy of the ASPA gene. Carriers themselves are not affected by the disease. How is the disease transmitted ? When two unaffected carriers of the ASPA gene mutation become parents, then for each pregnancy: 
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Does it affect one's health to be a carrier of the Canavan disease genetic mutation ? No. Carriers of the ASPA gene mutation are completely unaffected by Canavan disease. Does Canavan disease affect only males ? No. Canavan disease can affect both males and females. Is it possible to test to see if a person is a carrier of the faulty ASPA gene ? Yes. Although there is no cure or effective treatment for Canavan disease, genetics carrier testing is available. Extensive genetics carrier testing for Tay-Sachs disease in various regions of the world has lead to its virtual elimination in these areas. Why is a person's ancestry relevant to genetics carrier testing ? There are different faults (mutations) found in genes. Some faults are specific to particular ethnic groups or regions in the world. The various laboratory tests being used have each been designed to detect specific genetic faults that are most common among individuals who are of particular ancestries, origin and descent. For whom is genetics carrier testing for CD relevant ? Testing is available for all men and women over the age of 16. However, it is particularly relevant to Jewish men and women. How is testing performed ? A simple blood or mouth wash test is all that you require to check whether or not you are a carrier of the faulty gene. What confidence can I have in the test results ? The accuracy of the results will depend on your ancestry. Some mutations are specific to certain regions of the world or certain ethnic groups and therefore tests gave a greater confidence with people from these areas. Any Canavan disease mutations will be reconfirmed in a second independent laboratory. The testing laboratory has been accredited by the International tay-Sachs disease Testing Quality Control and Data Collection. If I do not have a family history of Canavan disease do I need to be tested ? Yes. Over 95% of the couples with children affected with Canavan disease have no family history of the disease because the ASPA gene mutation is silently passed down through the generations. However, if there is a family history, then the risk is much greater. People who have a known family history of Canavan disease should seek further information through genetics counselling (telephone: (61) 2 9926 7324). Can any other conditions be tested for at the same time ? Yes. The laboratory can also test for some other inherited disorders at the same time as testing for Canavan disease. Testing is already available for Tay-Sachs disease and cystic fibrosis, which are genetic conditions inherited in a similar way to Canavan disease. Over the next few years, testing will also be available for other inherited conditions. You will be asked to provide written consent if you want us to test for any additional conditions in the future. |
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Contact: PaLMS Laboratory & Community Genetics: Ph:992-68899 Fax:9926-8484 Email:aproos@doh.health.nsw.gov.au | |||