Homozygous Paternally Inherited ASPA Variant in a Patient with Canavan Disease

Introduction: Canavan disease is an autosomal recessive disorder that causes accumulation of N-acetyl ASPArtic acid in the brain due to ASPArtoacylase deficiency with homozygous or compound heterozygous pathogenic variants in the ASPA gene located on the short arm of chromosome 17. Clinical findings are hypotonia, progressive macrocephaly, deafness, nystagmus, blindness, and brain atrophy. Case Presentation: A one-year-old female case was evaluated in our medical genetics clinic for hypotonia, nystagmus, and strabismus. Chromosome analysis and array-comparative genomic hybridization showed no pathology. Clinical exome sequencing by next-generation sequencing was performed and a homozygous likely pathogenic variant NM_000049.4(ASPA):c.857C > A p.(Ala286Asp) was identified. Sanger sequencing of the parents showed that the index case had a homozygous genotype, the father was heterozygous and the mother had a wild genotype for the identified variant in ASPA. A single nucleotide polymorphism (SNP) array test was planned for the family to explain this homozygosity and a loss of maternal heterozygosity was determined in the 17p13.3-p13.2 region of the ASPA gene. Conclusion: In this report, we aimed to present the first case of Canavan disease with maternal loss of heterozygosity in the ASPA gene. (c) 2024 S. Karger AG, Basel