Canavan Disease

What is UNITY Fetal Risk™ Screen for Canavan disease?

UNITY Fetal Risk Screen is a carrier screening and fetal risk assessment for your pregnancy all in one convenient blood test. The first step is identifying if you are a carrier for Canavan disease. If you are not a carrier for Canavan disease, your baby’s risk of having Canavan disease is extremely low. If you are a carrier and currently pregnant, UNITY Fetal Risk Screen will automatically perform a fetal risk assessment using cfDNA to tell you if your baby’s risk of having Canavan disease is high or low. 

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The American College of Obstetricians and Gynecologists recommends Canavan disease carrier screening for anyone planning to start a family or those who are already pregnant that have Ashkenazi Jewish ancestry and/or family history of Canavan disease.

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What is Canavan disease?

Canavan Disease is an inherited condition that affects the brain. There are two types of Canavan disease: typical Canavan disease (infantile-type) which is more severe and atypical Canavan disease which is milder. 

Infants with typical Canavan Disease may appear normal at birth, but usually develop symptoms between 3-6 months of age. These symptoms can include a large head, poor muscle control, and developmental delays. Most children with Canavan disease develop life-threatening complications by 10 years of age. Currently, there is no cure for Canavan disease. Treatment depends on the specific symptoms that the affected person has.

Symptoms of atypical Canavan disease usually develop later than in typical Canavan disease, with developmental delays appearing in early childhood or adolescence. Coordination problems and difficulty walking may occur in some individuals, as well as seizures and vision loss. The type and severity of symptoms vary.

Genetic testing can sometimes predict which condition is more likely, however, it cannot always provide definitive answers. 

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How is Canavan disease inherited?

Canavan disease is an autosomal recessive condition. This means that a person must inherit two non-functional ASPA genes, one from each of their parents, to be affected with Canavan disease. Parents who carry one functional gene and one non-functional gene are known as carriers and typically show no symptoms.

If both parents are carriers of Canavan disease, there is 25% chance with each pregnancy that their child will inherit two non-functional genes and develop Canavan disease, a 50% chance that their child will inherit one non-functional gene and be a carrier like their parents, and a 25% chance that their child will inherit two functional genes and not be affected or a carrier.

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Who should consider screening for Canavan disease? 

Carrier screening for Canavan disease is recommended for anyone planning to start a family or those who are already pregnant that have Ashkenazi Jewish ancestry and/or family history of Canavan disease. UNITY Fetal Risk Screen is a simple blood test to determine your carrier status and the risk of having a baby with Canavan disease. If your results show a high risk of any of the conditions screened, you can discuss additional testing either before or after your delivery with your healthcare provider or one of our genetic counselors. 

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UNITY Fetal Risk Screen Carrier Screening & Fetal Risk Assessment (cfDNA for recessive conditions) workflow

Test as early as 9 weeks

Your blood sample can be collected in the doctor’s office, at a local lab, or through our mobile services. Your blood sample is shipped to our CAP/CLIA certified laboratory in northern California.

UNITY Aneuploidy™  Screen + UNITY Fetal RhD™  and Fetal Antigen™  results as early as 10 weeks
Within about one week from lab receipt, your doctor will receive the baby’s risk score for aneuploidies (chromosome conditions) and fetal RhD and fetal antigens (if added). You will receive a text or email indicating your results are available on our portal, or your healthcare provider may call you with the results.

Carrier status + fetal risk assessment results as early as week 11
Within about two weeks from lab receipt, your doctor will receive the results of your maternal carrier status testing and fetal risk assessment. If you were found to be a carrier for any of the recessive conditions, fetal risk assessment is automatically run to determine your baby’s risk of being affected. You will receive a text or email indicating your results are available on our portal, or your healthcare provider may call you with the results.

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What do Canavan disease screening results mean?

Your UNITY Fetal Risk Screen results will tell you if you are a carrier for Canavan disease, or other recessive conditions. Then, if you are currently pregnant and a carrier for one or more of the conditions screened, a fetal risk assessment using cfDNA will automatically be performed on your sample. Your UNITY Fetal Risk Screen report will show your baby's risk for being affected with Canavan disease. 

If your results show a high-risk, your healthcare provider will discuss the recommended confirmatory testing that can be performed before or after delivery.

UNITY Fetal Risk Screen results are not diagnostic, so there is always the option for additional confirmatory testing to be performed. You can discuss your options and recommendations with your provider or one of our genetic counselors:

• Before Birth:
  Testing during pregnancy can be performed by obtaining a sample of placenta (chorionic villus sampling or CVS) or fluid around your baby (amniocentesis) which both contain DNA that is representative of your baby.  A CVS is ideally performed between 10 to 13 weeks in pregnancy while an amniocentesis is typically performed between 15 to 24 weeks in pregnancy.  Both procedures are generally safe, but have a small risk for pregnancy complications, including miscarriage.

• After Birth: 
  Testing for your baby can be performed after birth through a blood test as a newborn or with your baby’s pediatrician. 

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Frequently Asked Questions

Is there a cure for Canavan disease? 

Currently, there is no cure for Canavan disease. However, clinical trials are ongoing for gene and enzyme therapies. 

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How is Canavan disease treated? 

Treatment mainly focuses on managing the symptoms and improving the quality of life for those affected. Individuals with Canavan disease benefit from early intervention programs and are managed by a multidisciplinary care team, including neurologists, gastroenterologists, nutritionists, and other healthcare providers.

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What is the difference between typical and atypical Canavan disease?
Typical Canavan Disease: Around 85-90% of those with Canavan disease have the typical form, which often presents with more severe symptoms in infancy. Common symptoms of typical Canavan disease include a larger head size, poor muscle control, seizures and developmental delays. 

Atypical Canavan Disease: Around 10-15% of those with Canavan disease have the atypical form, which may have later onset and less severe symptoms. Possible symptoms of atypical Canavan disease include developmental delays appearing in early childhood or adolescence, coordination problems and vision loss. The type and severity of symptoms vary.

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Treatment & Resources

• National Organization of Rare Diseases
• Canavan Foundation
• National Tay Sachs and Allied Diseases Association