Novel HEXA variants in Korean children with Tay-Sachs disease with regression of neurodevelopment from infancy

Mol Genet Genomic Med. 2021 Jun;9(6):e1677. doi: 10.1002/mgg3.1677. Epub 2021 Apr 3.

Abstract

Background: Tay-Sachs disease (TSD) is a lysosomal storage disease caused by mutations in the HEXA gene that encodes the HexosaminidaseA (HEXA) enzyme. As HEXA normally functions to degrade the protein GM2-ganglioside in lysosomes, decreased levels of HEXAcauses an accumulation of the protein and leads to neurological toxicity. Typical clinical manifestations of TSD include neurodevelopmental regression, muscle weakness, hypotonia, hyperreflexia, ataxia, seizures, and other neurological symptoms. It is quite rare in Asian populations, wherein only two cases have been reported in Korea to date.

Methods: Clinical records, radiological assessments, and laboratory findings, such as plasma hexosaminidase assay and HEXA analysis, were extracted from the medical records of three (1 male and 2 female) independent Korean children with infantile form of Tay-Sachs disease.

Results: All three children presented with neurodevelopmental regression and strabismus at around 8 months of age. Presence of cherry-red spots in the macula led to conduction of biochemical and genetic studies for TSD confirmation. The plasma hexosaminidase assay revealed decreased HEXA activity and low to normal total hexosaminidase activity. Similarly, genetic analysis revealed 4 variants from 6 alleles, including 2 previously reported and 2 novel variants, in the HEXA gene.

Conclusion: We presented three Korean children, who were recently diagnosed with infantile-type TSDvia enzyme assay and genetic analysis. Furthermore, results showed that fundus examination can be helpful for early diagnosis of children with neurodevelopmental regression.

Keywords: GM2-gangliosidosis; Tay-Sachs disease; cherry-red spot; hexosaminidase A deficiency; neurodevelopmental regression.

Publication types

  • Case Reports

MeSH terms

  • Child, Preschool
  • Disease Progression
  • Early Diagnosis
  • Female
  • Fundus Oculi
  • Humans
  • Infant
  • Male
  • Mutation
  • Republic of Korea
  • Tay-Sachs Disease / diagnosis
  • Tay-Sachs Disease / genetics*
  • beta-Hexosaminidase alpha Chain / blood
  • beta-Hexosaminidase alpha Chain / genetics*

Substances

  • HEXA protein, human
  • beta-Hexosaminidase alpha Chain