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Unique enamel phenotype associated with amelogenin gene (AMELX) codon 41 point mutation
D B Ravassipour1, P S Hart, T C Hart
1Department of Pediatric Dentistry, University of North Carolina, Chapel Hill 27599, USA.
Journal of Dental Research
|September 27, 2000
Summary
A specific mutation in the amelogenin gene (AMELX) causes X-linked amelogenesis imperfecta (AI). This genetic change leads to consistent enamel defects, including prism holes and altered crystallite structure.
Area of Science:
- Genetics
- Biochemistry
- Dentistry
Background:
- Amelogenesis imperfecta (AI) encompasses various enamel phenotypes caused by amelogenin gene (AMELX) mutations.
- Specific mutations are hypothesized to cause distinct AI phenotypes.
Purpose of the Study:
- To investigate the enamel composition and structure linked to a particular AMELX mutation in families with X-linked AI.
- To correlate a specific genetic defect with observed enamel abnormalities.
Main Methods:
- AMELX exon amplification and sequencing for mutational analysis.
- Microscopic examination (light, scanning, transmission electron microscopy) of affected and normal teeth.
- Immunolocalization of amelogenin and amino acid analysis of enamel proteins.
Main Results:
- All affected individuals shared a common AMELX point mutation (codon 41 C to A).
- AI enamel exhibited opacity, widespread prism defects, and more radiolucent, less uniform crystallites.
- Amelogenin localized to crystallites in affected enamel, with increased amelogenin-like protein content (0.95% vs. 0.13% in normal).
Conclusions:
- A missense point mutation at codon 41 of the AMELX gene results in a consistent X-linked AI phenotype.
- This mutation affects enamel structure and composition, leading to characteristic defects.