Novel dentin phosphoprotein frameshift mutations in dentinogenesis imperfecta type II

Area of Science:

• Genetics
• Biochemistry
• Dentistry

Background:

• The dentin sialophosphoprotein (DSPP) gene is crucial for dentin formation, encoding proteins like dentin phosphoprotein (DPP).
• DSPP gene mutations are linked to hereditary dentin defects, specifically dentinogenesis imperfecta (DGI).

Purpose of the Study:

• To investigate the genetic basis of dentinogenesis imperfecta type II in three Korean families.
• To identify novel mutations within the DSPP gene associated with DGI type II.

Main Methods:

• Candidate gene sequencing of DSPP exons and exon-intron boundaries.
• Polymerase chain reaction (PCR) amplification and direct sequencing.
• Allele-specific cloning of DSPP exon 5.

Main Results:

• Identified two novel single base pair deletional mutations in the DSPP gene: c.2688delT and c.3560delG.
• These mutations introduce hydrophobic amino acids into the hydrophilic repeat domain of DPP.
• Affected individuals exhibited rapid pulp chamber obliteration; c.3560delG caused mild discoloration, while c.2688delT resulted in more pronounced changes.

Conclusions:

• The identified DSPP mutations are associated with dentinogenesis imperfecta type II.
• These findings contribute to understanding the molecular pathogenesis of DGI type II.
• The study sheds light on the role of DSPP in dentin biomineralization and disease.