Deep Intronic SVA_E Retrotransposition as a Novel Factor in Canavan Disease Pathogenesis

Area of Science:

• Genetics
• Neuroscience
• Molecular Biology

Background:

• Canavan disease (CD) is a rare, autosomal recessive leukodystrophy.
• It is caused by pathogenic variants in the ASPA gene, leading to developmental delay and macrocephaly.
• Biochemical diagnosis relies on elevated N-acetylaspartic acid levels, with variable clinical presentations.

Purpose of the Study:

• To identify the genetic cause in Canavan disease patients with unexplained diagnoses.
• To investigate the role of novel genetic elements in CD pathogenesis.
• To improve diagnostic accuracy and guide therapeutic strategies for Canavan disease.

Main Methods:

• Targeted long-read sequencing of the ASPA gene.
• Haplotype analysis to link genetic elements.
• Functional characterization of retrotransposable elements and mRNA degradation.

Main Results:

• An SVA_E retrotransposable element in intron 4 of the ASPA gene was identified in five patients.
• This element was previously missed by standard short-read sequencing methods.
• The SVA_E element, linked to an intron 1 variant, promotes efficient mRNA degradation.

Conclusions:

• The SVA_E element is a significant cause of Canavan disease, particularly in cases with previously unidentified variants.
• This discovery enhances the precision of genetic diagnostics for Canavan disease.
• Improved genetic understanding facilitates better family counseling and potential targeted therapies.