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Decreased guanine nucleotide exchange factor activity in eIF2B-mutated patients
Anne Fogli1, Raphael Schiffmann, Lynne Hugendubler
1INSERM UMR 384, Faculté de Médecine, 28 place Henri Dunant, Clermont-Ferrand, France.
European Journal of Human Genetics : EJHG
|April 1, 2004
Summary
Mutations in eukaryotic initiation factor 2B (eIF2B) cause leukodystrophies. Reduced eIF2B guanine nucleotide exchange factor (GEF) activity in patients
Area of Science:
- Neuroscience
- Genetics
- Cell Biology
Background:
- Mutations in eukaryotic initiation factor 2B (eIF2B) subunits are linked to various leukodystrophies, including Cree leukoencephalopathy, childhood ataxia with central hypomyelination/leukodystrophy with vanishing white matter, and ovarioleukodystrophy.
- Disease severity exhibits a continuum, ranging from fatal infantile forms to adult-onset cases with no neurological decline, correlating with age of onset and specific amino-acid substitutions.
Purpose of the Study:
- To investigate the functional consequences of eIF2B mutations.
- To establish a correlation between eIF2B guanine nucleotide exchange factor (GEF) activity and disease severity.
Main Methods:
- Measured the GEF activity of eIF2B in transformed lymphocytes from 30 patients with eIF2B mutations.
- Compared GEF activity to 10 unaffected heterozygotes and 22 controls without eIF2B mutations.
Main Results:
- All mutated cells displayed a significant 20-70% decrease in eIF2B GEF activity.
- The degree of GEF activity reduction correlated with the age of disease onset.
Conclusions:
- A deficiency in eIF2B GEF activity is implicated in the pathogenesis of eIF2B-related encephalopathies.
- Evaluating GEF activity in transformed lymphocytes offers a viable alternative to direct gene screening and serves as a cellular model for therapeutic strategy development.