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A new frameshift mutation encoding a truncated amelogenin leads to X-linked amelogenesis imperfecta
S R Greene1, Z A Yuan, J T Wright
1Department of Anatomy and Histology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Archives of Oral Biology
|February 13, 2002
Summary
A genetic mutation in amelogenin (AMELX) causes severe enamel defects. This study identifies a specific deletion in the AMELX gene, leading to amelogenesis imperfecta, highlighting the C-terminal region's importance for enamel thickness.
Area of Science:
- Biochemistry
- Genetics
- Developmental Biology
Background:
- Amelogenin proteins are crucial for dental enamel mineralization.
- Mutations in the X-chromosomal AMELX gene cause amelogenesis imperfecta.
- The C-terminal region's role in enamel formation requires further elucidation.
Purpose of the Study:
- To investigate the genetic basis of a severe hypoplastic enamel phenotype.
- To identify the specific mutation in the amelogenin (AMELX) gene responsible for the observed enamel defect.
- To understand the functional significance of the amelogenin C-terminal region.
Main Methods:
- Genetic sequencing of the amelogenin (AMELX) gene in affected individuals and family members.
- Analysis of the identified mutation's impact on the amelogenin protein structure and function.
- Phenotypic assessment of dental enamel in affected individuals.
Main Results:
- A single base deletion was identified at codon 110 in the AMELX gene of an adult male with severe hypoplastic enamel.
- The mutation cosegregated with the phenotype in the family, with the mother also being a carrier.
- The frameshift mutation alters the amelogenin protein, deleting key regions and adding a cysteine-rich segment, despite predicting over 60% intact protein.
Conclusions:
- This specific AMELX gene deletion causes a severe amelogenesis imperfecta phenotype.
- The C-terminal region of amelogenin is essential for the formation of normally thick dental enamel.
- Understanding these mutations provides insights into enamel development and genetic disorders.