Hyperekplexia Associated With Compound Heterozygote Mutations in the Beta-Subunit of the Human Inhibitory Glycine Receptor (GLRB)

Hum Mol Genet. 2002 Apr 1;11(7):853-60. doi: 10.1093/hmg/11.7.853.

Abstract

Hyperekplexia (MIM: 149400) is a neurological disorder characterized by an excessive startle response which can be caused by mutations in the alpha1-subunit (GLRA1) of the heteropentameric human inhibitory glycine receptor (hGlyR). These receptors facilitate fast-response, inhibitory glycinergic neurotransmission in the brainstem and spinal cord leading to a rapid modification and reduction of the excitatory startle response. Mutations in the beta-subunit of GlyR (glrb) occur in a murine model of hyperekplexia (spastic), but have not been detected in human hyperekplexia. Following mutation analysis of the human beta-subunit of hGlyR (GLRB) in a cohort of 22 hyperekplexia patients, we provide evidence to confirm that GLRB mutations can cause human hyperekplexia. A missense (G920A resulting in G229D) and a splice site mutation (IVS5+5G-->A) occurred together in a compound heterozygote with a transient hyperekplexia phenotype. Exon trap analysis revealed that IVS5+5G-->A results in the exclusion of exon 5 from GLRB transcripts. Electrophysiological studies showed reduced sensitivity to agonist mediated activation of the alpha1beta (G229D) GlyR suggesting that GlyR beta-subunits are not restricted to conferring modulatory influences and maintaining structural integrity, but may also play a functional role in hGlyR ligand binding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child, Preschool
  • Heterozygote*
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Mutation*
  • Nervous System Diseases / genetics*
  • RNA Splice Sites
  • Receptors, Glycine / genetics*
  • Sequence Analysis, DNA

Substances

  • GLRB protein, human
  • RNA Splice Sites
  • Receptors, Glycine