Translated Mutant DSPP mRNA Expression Level Impacts the Severity of Dentin Defects

Area of Science:

• Genetics
• Molecular Biology
• Dentistry

Background:

• Hereditary dentin defects are traditionally classified into dentinogenesis imperfecta (DGI) and dentin dysplasia (DD).
• Mutations in the dentin sialophosphoprotein (DSPP) gene are linked to DGI types II and III and DD type II, suggesting these are allelic disorders.
• Understanding the molecular basis of DSPP mutations is crucial for diagnosing and managing these conditions.

Purpose of the Study:

• To investigate the genetic basis of hereditary dentin defects in families with varying clinical phenotypes.
• To identify novel mutations in the DSPP gene and elucidate their impact on pre-mRNA splicing.
• To correlate DSPP gene mutations with the clinical severity of dentin defects.

Main Methods:

• Recruitment of three families exhibiting phenotypes ranging from DGI-III to DD-II.
• Conducting mutational analysis using candidate gene analysis and whole-exome sequencing.
• Performing splicing assays to evaluate the functional consequences of identified DSPP mutations.

Main Results:

• Identification of three novel DSPP mutations: c.52-2del, c.135+1G>C, and c.135G>A (p.Gln45=).
• All identified mutations were found to affect pre-mRNA splicing of the DSPP gene.
• A correlation was observed between the expression level of DSPP exon 3 deletion transcripts and the severity of dentin defects.

Conclusions:

• The study expands the known mutational spectrum of the DSPP gene.
• Novel DSPP mutations impacting pre-mRNA splicing are a significant cause of hereditary dentin defects.
• DSPP splicing alterations play a critical role in determining the clinical severity of dentin defects, advancing our understanding of molecular pathogenesis.