The Invitae Canavan Disease Test analyzes ASPA, the gene that is associated with Canavan disease, a rare leukodystrophy. Genetic testing of the ASPA gene may confirm a diagnosis and help guide treatment and management decisions.
Canavan disease is a rare neurodegenerative disorder that is characterized by the degeneration of the myelin sheath that insulates nerve cells (leukodystrophy). The loss of myelin leads to progressive neurological damage. The most common form of Canavan disease starts in infancy, with infants appearing normal for the first few months of life and then, by age 3–5 months, presenting with macrocephaly, hypotonia, and developmental delay. There is a less-common and more mild form of this disorder, in which symptoms first present in late childhood or early adolescence.
Patients with Canavan disease typically have increased levels of N-acetylaspartic acid (NAA) in urine; however, patients with the milder form of the disease may not always have increased urine NAA. Therefore, molecular testing should be considered in patients with clinical suspicion of Canavan disease, despite negative urine results.
Pathogenic variants are found in more than 98% of Ashkenazi Jews and more than 87% in non-Ashkenazi Jewish individuals.
Canavan disease is inherited in an autosomal recessive manner.
Canavan disease is more common among Ashkenazi Jews. Carrier frequency in Ashkenazi Jews is 1 in 57–82. Carrier frequency in the general population is thought to be much lower.
Infants with evidence of white matter disease or elevated NAA in blood, cerebrospinal fluid, and urine should have molecular confirmation of Canavan disease. For juvenile or mild cases, neuroimaging may not be suggestive and urine NAA may only be slightly elevated.
Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).
Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence, and select noncoding variants. Our assay provides a Q30 quality-adjusted mean coverage depth of 350x (50x minimum, or supplemented with additional analysis). Variants classified as pathogenic or likely pathogenic are confirmed with orthogonal methods, except individual variants that have high quality scores and previously validated in at least ten unrelated samples.
Our analysis detects most intragenic deletions and duplications at single exon resolution. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. If you are requesting the detection of a specific single-exon copy number variation, please contact Client Services before placing your order.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|