Please call the Department of Medical Genetics to schedule an appointment for a genetic counselling session at 514-412-4427 if not already booked.
Canavan disease (CD)
CD is caused by the absence of a molecule responsible for the breakdown of a specific substance. As this substance is not broken down, it accumulates in the body and is toxic for the central nervous system (brain and spinal cord). This causes changes in the texture of the brain matter.
CD is a severe condition that worsens with time. At birth, babies with CD are normal. Symptoms vary and appear between ages 3 to 5 months with muscle weakness and when, due to a bigger than average head size, head control is problematic. As the weakness becomes more severe and muscles become stiffer, infants fail to achieve new motor and language skills such as rolling, sitting, standing, walking or talking. Infants learn to interact socially as they can laugh, smile and reach for objects. As children age, they develop sleeping difficulties as well as swallowing problems and seizures. They often experience gradual loss of vision and hearing leading to blindness and deafness. Some children die in childhood whereas others live into their teens.
There is no cure for CD. Care is offered to improve the children’s quality of life and includes controlling for adequate nutrition and hydration, managing infections, protecting the airways and using medication to control seizures. Physical therapy and special education programs can help with muscle weakness.
Genetics
As you are both carriers of the same condition, your probabilities are 1/4 of having a child who is affected, 1/2 of having a child who is a carrier and 1/4 of having a child who is not a carrier.
Pregnancy options
Two options are available to test your pregnancy. One is performed in the first trimester of pregnancy and the other is performed from the second trimester. Both procedures allow one to know whether the baby is affected by the condition, but both are associated with an increased risk of pregnancy loss (miscarriage).
Another option allows one to know if the baby will be affected with the condition before getting pregnant. The procedure is done with the help of assisted reproductive technologies. Eggs and sperm are collected and fertilized in the laboratory. After fertilization, embryos are tested for the specific condition and only unaffected embryos are implanted in the mother’s womb.
Choosing a diagnostic procedure as a pregnancy option is a couple`s personal choice. Other non-diagnostic options are also available including 1) choosing not to test the pregnancy; 2) using an egg and/or a sperm donor, who is someone who is not a carrier of the condition; or 3) adopting a child.