GlyRs formed from alpha 1R271K subunits showed a reduction of beta-alanine and taurine affinities and maximal inducible currents; the mutants alpha 1R271Q and alpha 1R271L associated with human hyperekplexia gave no responses to these ligands.
Thus, only clinically typical hyperekplexia appears to be consistently associated with GLRA1 mutations, and these affect a specific extracellular domain of the protein.
However, recessive transmission is seen in the mouse mutant spasmodic which resembles startle disease phenotypically and is also associated with mutations in Glra 1.
Based on the identical phenotypes of mouse lines carrying mutant alleles of the alpha 1 and beta subunit genes, GLRB was assumed to be a candidate gene for those cases of hyperekplexia that cannot be associated with mutations of GLRA1.
Population studies reveal the unique association of each mutation with disease, and reveals that a proportion of sporadic hyperekplexia is accounted for by the homozygous inheritance of recessive GLRA1 mutations or as part of a compound heterozygote.
We investigated the molecular basis of hyperekplexia (STHE), an inherited neurological disorder characterised by neonatal hypertonia and an exaggerated startle response, in a kindred and identified a novel missense mutation in the pore-lining M2 domain of the alpha1 subunit of the glycine receptor (GLRA1).
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).
A novel recessive hyperekplexia allele GLRA1 (S231R): genotyping by MALDI-TOF mass spectrometry and functional characterisation as a determinant of cellular glycine receptor trafficking.
In its familial form, hyperekplexia has been associated with both dominant and recessive mutations of the GLRA1 gene encoding the glycine receptor alpha1 subunit (GlyRalpha1), which mediates inhibitory transmission in the spinal cord and brainstem.
Different from the dominant trait of clinical hyperekplexia associated with GLRA1 (P250T), wildtype subunits dominated the functional properties of mixed receptor complexes in the recombinant system.
Statistical coassembly of glycine receptor alpha1 wildtype and the hyperekplexia mutant alpha1(P250T) in HEK 293 cells: impaired channel function is not dominant in the recombinant system.
The disease caused by mutation in GLRB in mice supports the notion that human hyperekplexia with no detectable mutations in GLRA1 may harbor mutations in GLRB.
Mice deficient in gephyrin develop a hereditary molybdenum cofactor deficiency and a neurological phenotype that mimics startle disease (hyperekplexia).
Mutations in this 'hot spot' domain of GLRA1 are frequent in autosomal dominant hyperekplexia but are not usually seen in the autosomal recessive form of the disease in which both the M1 and the carboxy terminal domains have been implicated.
Hyperekplexia (HE), or startle disease, is usually a familial disorder associated with mutations in the glycine receptor alpha1 subunit gene (GLRA1), characterised by exaggerated startle reactions to unexpected auditory, somaesthetic and visual stimuli.
The previously identified hyperekplexia mutation GLRA1(P250T), located within the intracellular TM1-2 loop of the GlyR alpha1 subunit, results in altered receptor activation and desensitization.
Hyperekplexia is a human neurological disorder characterized by an excessive startle response and is typically caused by missense and nonsense mutations in the gene encoding the inhibitory glycine receptor (GlyR) alpha1 subunit (GLRA1).