How Can Our Child Have Canavan Disease If We're Not Jewish?

A diagnosis can be especially confusing when your family does not fit the group most often associated with the condition. It is important to know that nothing you or your partner did caused Canavan disease.

While Canavan disease is strongly associated with Ashkenazi Jewish ancestry, it is not exclusive to this group. Anyone of any ethnicity can carry a pathogenic variant (a disease-causing genetic change) in the ASPA gene, which provides instructions for aspartoacylase, an enzyme involved in breaking down N-acetylaspartic acid in the nervous system ^[1].

Because Canavan disease is an autosomal recessive genetic condition, a child will be born with it if both parents pass down a mutated copy of the gene, regardless of their ethnic or cultural background ^[1].

How Inheritance Works

Carriers of an ASPA gene variant are typically healthy and do not know they carry it. When both biological parents are carriers of a pathogenic ASPA variant, each pregnancy has a:

• 25% chance that the child will have Canavan disease (inheriting the variant from both parents).
• 50% chance that the child will be a healthy carrier like the parents (inheriting one variant).
• 25% chance that the child will not have the disease and will not be a carrier.

These recurrence risks apply to all families facing this condition, and a genetic counselor can help you review options for any future pregnancies ^[1].

Understanding the Ashkenazi Jewish Connection

The misconception that Canavan disease only affects Jewish families stems from how frequently it occurs in that specific population. In the Ashkenazi Jewish community, the carrier frequency (the proportion of people who carry a variant) is much higher (about 1 in 40), and the overall prevalence (the estimated number of cases in the population) is approximately 1 in 6,400 to 1 in 13,500 ^[2]. Specific genetic changes, such as the p.Glu285Ala variant, are highly concentrated in this group ^[3].

Because of this higher concentration, carrier screening and public awareness have historically focused heavily on people of Ashkenazi Jewish descent.

Canavan Disease Across the Globe

Although the disease is less frequent overall outside of Ashkenazi communities, Canavan disease is diagnosed in families from many different ethnic backgrounds worldwide ^[4][5]. Researchers have documented cases in Arab, Iranian, Pakistani, Egyptian, and Indian families, among others ^[4][6][7].

Different populations often have their own specific variants of the ASPA gene. For example, in the Telugu Devanga Chettiar community of southern India, researchers identified a distinct genetic variant resulting in a carrier frequency of about 1 in 23 within that specific community ^[8][9].

Additionally, consanguinity (when parents are closely related by blood, such as cousins) can neutrally increase the chance that both parents carry the same rare genetic variant ^[4]. However, consanguinity does not cause the disease on its own, and the disease routinely occurs in completely unrelated parents who both happen to carry ASPA variants ^[1].

Genetic Testing for Diagnosis vs. Carrier Screening

It is important to understand the difference between diagnostic testing (finding out what is making a child sick) and carrier screening (checking if healthy adults carry a variant).

• Targeted carrier panels are often designed to look primarily for the most common variants (such as those in the Ashkenazi Jewish population). If a relative takes a targeted panel, a rare variant specific to your family might be missed ^[10].
• Diagnostic testing for a child usually involves full sequencing of the ASPA gene to look for any possible changes.

Sometimes, standard sequencing can miss complex genetic changes, like structural insertions (extra pieces of DNA). When a child clearly has symptoms of Canavan disease but standard diagnostic tests do not find both variants, doctors may recommend advanced methods like whole-exome sequencing or long-read sequencing to find the specific genetic changes ^[10][11].

What This Means for Your Family

Once your child’s exact ASPA variants are identified, this information is crucial for the rest of the family. The specific variant does not perfectly predict your child’s disease severity—care is guided by their actual symptoms rather than their genetic test results.

However, knowing the exact variant means that your extended relatives (such as adult siblings, aunts, uncles, and cousins) can undergo testing for your family’s exact variants if they are planning a pregnancy. A genetic counselor can help guide which family members might benefit from this testing.