Journal of Human Genetics· 2026Q2
Novel SLC6A9 variants in an adult presenting with GlyT1 encephalopathy
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- Q2SCImago
- 2026year
Short summary
A 27-year-old patient, the oldest reported with GlyT1 encephalopathy, was identified with two novel SLC6A9 variants, offering new phenotypic insights and potential prognostic indicators for this ultra-rare disorder.
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Key points
- A 27-year-old patient with GlyT1 encephalopathy, caused by novel compound heterozygous SLC6A9 variants, is the oldest reported case.
- The patient exhibited typical GlyT1 encephalopathy features including hypotonia, hypertonicity, respiratory failure, exaggerated startle, and arthrogryposis.
- Clinical stabilization occurred after early childhood, and perampanel provided significant benefit for the exaggerated startle.
- Unexplained visual loss was noted, possibly related to GlyT1's role in retinal amacrine cells, though this mechanism is speculative.
AI-generated from the title and abstract; the full text is not read.
Abstract
Only 14 individuals have been thus far described with GlyT1 encephalopathy due to biallelic variants in the SLC6A9 gene and the phenotypic picture is incomplete. Early mortality has been high, with only two known to survive into infancy. We report a 27-year-old individual who, to our knowledge, is the eldest person described with this ultra-rare disorder and who brings new phenotypic insights alongside potential prognosis for younger individuals. He is compound heterozygous for two novel SLC6A9 variants. He shares many unifying clinical features, including neonatal hypotonia with later hypertonicity, respiratory failure, exaggerated startle and arthrogryposis. Clinical course stabilised after early childhood. Perampanel was of significant benefit for the exaggerated startle. Significant visual loss is unexplained. It may relate to the essential role of GlyT1 in retinal amacrine cells, although this mechanism remains speculative.
The authors' abstract, as published at the source. Journal of Human Genetics, 2026 · DOI ↗
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Field: Biochemistry (Biochemistry, Genetics and Molecular Biology)
BiochemistryBiochemistry, Genetics and Molecular Biology